Speed Demos Archive - Sonic 3 & Knuckles

Sonic 3 & Knuckles was released in 1994 as two separate game cartridges: Sonic 3 came in February and represents the first half of the game, while Sonic & Knuckles, representing the second half, arrived in October. New types of Shields, twice the number of Chaos Emeralds to collect and a new playable character, Knuckles, with his own special routes through the game distinguish Sonic 3 & Knuckles from its predecessors.

Note: Runs on standalone Sonic 3 or Sonic & Knuckles are not allowed. Runs must be performed on the full game.

Thanks go out to:
The SDA crew - too big to name everyone now, you guys are still awesome!
Nate - for his capture and encoding genius

The Sonic Center - www.soniccenter.org - Still the most comprehensive resource on competitive Sonic gameplay anywhere.
HDL and werster - I owe a huge debt to HDL in particular, I stopped playing this game for a while before he showed up in SpeedrunsLive, and he, werster and I started chatting and strategising, and my consistency in some of the tougher parts of the run is greatly increased because of all three of us working together on things. In particular, the method for the Ice Cap glitch is almost entirely his.
Sprint, nitsuja, upthorn, marzojr - The TASing crew for this game. nitsuja in particular took the game to a whole new level, and the latter two have built upon his work.
ORKAL - Posted an excellent series of videos on Youtube highlighting just how broken this game really is. I highly recommend you check them out if you're interested in the game.
Anyone who's ever posted a Youtube video of the full game or even a single level - I have no doubt that if I've watched it, and it was even a little bit good, I've taken something from you. Every little bit counts!

Speedrun history:
1/12/06 - 36:55 - mike89
19/8/10 - 32:12 - mike89
14/10/11 - 26:28 - mike89

After I submitted that run in August 2010 I figured that most of the game had been worked out by now. Well, I guess not. :P This run features a multitude of new glitches, from the face-palmingly obvious to the frame-precise to the outright bizarre. If you think you know this game, I guarantee you'll learn something new.

Unfortunately, some of these glitches have really killed my desire to play this game as Knuckles any more. It requires some of the most intense tricks I've ever had to pull off in a run, and the worst of them, Flying Battery 2, is about 2/3 of the way through the run! That's why I ended up submitting this run, which I know has significant scope for improvement in it - realising that improvement would just result in more frustration at missing the glitches over and over.

This next part is going to be part of all my submissions for this game, so if you've already read it, skip it and go straight to the run analysis.

A Crash Course in Sonic 3 Level Design
Many of the tricks that enable the times for this game to reach the league they are in now have to do with the way levels in Sonic 3 are handled. In a sense, what you see is not always what you get, as the following tricks demonstrate:

* The Loopback Area
The map for each level in Sonic 3 is exactly 32768 pixels wide. Obviously the levels themselves are not all exactly that long: if you're able to go past the end of the stage, what you find is that the level restarts. However, in this "loopback" area, there are no sprites. There's a couple of ways to reach this area, but the easiest, and by far the most useful, is:

* Horizontal Underflow Glitch
At the start of any given level, you can try and go left right at the start, but of course the game won't let you, there's a hard lock there. However, because the game performs collision checks every frame, if you were able to move fast enough you could bypass the lock on the start of the stage and go "behind" the left edge of the stage. In memory, the game treats your x-coordinate as less than 0... which, being an unsigned integer, increases it to the maximum allowed by the map - 32767. This sends you to the aforementioned loopback area. Now the camera scrolls as fast as it can to the right trying to find you. The camera will stop scrolling under one of two conditions: either the game finds you, or it encounters a boss. Therefore, in any level which permits this, it is possible to skip from the left side of the level right to the boss!
Now before you start asking why I don't do this on every stage, remember that I mentioned you need a lot of speed to get through the left hand side. There's a few ways of doing it depending on the circumstances, but the most common is being ejected from a wall. That requires getting stuck in a wall in the first place, which requires some very select circumstances depending on the level. In the Knuckles run, it is used in Hydrocity 2, Ice Cap 2, Launch Base 1, and Flying Battery 2.

* Vertical Looping
The same also applies vertically: that is to say that if you cross the top of the screen, you're actually interacting with the structures on the -bottom- of the screen! In both the horizontal and the vertical cases, while you're off screen you can still move around freely, so if you know what you're interacting with and how to take advantage of it, you can move around just as quickly as if you could see what was going on.

* Wall Ejection
Once inside a wall, holding left sends you right, and holding right sends you left. Easy!

* Boss Coordinates
Sonic 3 has an interesting way of determining when you're in a boss room: it decides that you're in a boss room not when your character is within the coordinates that make up the room, but whether the -camera- lines up with the boss room! What this means is that when the camera is scrolling right to work out where you are, if you can reach the right y-coordinate at the time when the camera crosses the right x-coordinate, the camera will lock on the boss, and your character will magically appear in the boss room. In order to do this, you have to know what is in the loopback area and how to use it to your advantage.

* Vertical Screenwrap
Four levels (Marble Garden 1, Ice Cap 1, Sandopolis 2, and Sonic's Sky Sanctuary) are too tall for the game to fit into the space allocated to each level. To counteract this, in these four levels the kill plane is removed and you are able to fall infinitely, ie. the level wraps vertically. Using a similar methodology to horizontal underflow, if you duck down so that the screen goes down to its lowest point and then jump, the game thinks you're at the bottom of the screen and scrolls down to try and find you. While you're not in a loopback area in this instance, sprites don't exist if they're off screen, which enables you to pass through them.

* The Two Kinds of Timers
Timed objects in Sonic games can have one of two timing properties. Most timed objects operate on what's known as the universal timer, which starts as soon as the level is loaded (in the case of Sonic 3, this means that act 2 objects are actually timed from the start of act 1!). A handful of other objects, however, operate on a separate timer that only starts once you bring them on (or near) the screen. A good way to test this is in Flying Battery 1, in the room with the orange circle platforms that run through the tubes. The platform with the blades on the bottom is on the universal timer, while the orange circle platforms operate on the camera timer. If you enter this room at different times you'll catch the blade platform in different positions, while the orange circle platforms around it will stay in the same spot. This is actually highly important when you enter this room as Knuckles, because he has a hard time jumping onto the second set of orange platforms if they're too far away.

With that in mind, hopefully some of the decisions in the run will make more sense. On to it, then!

Angel Island 1 - 0:48 [-0:02 compared to previous run]
[0:48] Since I'm a couple of seconds faster at this act now, I kill time at the end of this act. The timed objects in act 2 actually start moving from the start of act 1, so this is a nice way to make sure the time I have to wait anyway doesn't count against me!

Angel Island 2 - 0:44 [-0:02]
[0:26] This is the platform I'm waiting for. I actually got here a bit quicker than usual, but I give myself a bit of leeway on this just because the tube prior to this can stop you dead and cost you about a second, and I like to be able to get it in that case (or just generally not playing the early part of the level perfectly).

Hydrocity 1 - 0:55 [0:00]
[0:00] Given Tails can fly straight out of this fall, you'd think Knuckles would be able to glide out of it, right? No, that would make way too much sense.
[0:24] The reason that this works is that Sonic games have two (or three, I forget) layers of background/foreground. In order to make a set up like this work (or even a loop), the game has invisible items called path switchers, which switch you between the foreground and background seamlessly. In this case, instead of running all the way through the loop and back again, you can just stop here and spindash because the path switcher is right near the point where the two paths actually meet.
[0:45] The quick kill on this boss relies on the fact that it actually exists far off screen as soon as the music starts. As such, the music gives you a vague idea of where it is at any given time before it appears on the screen, and by timing your spindash release you can get up to four hits just by bouncing on it. I kind of screwed it up here though, only got two, but I managed to use my invincibility time to good effect to get the rest and really fluked hit 5 knowing that if I didn't get it the fight would probably have been slow enough to warrant a restart.

Hydrocity 2 - 1:01 +2 [-0:17]
Note the +2 after the time: I add on two seconds because I died in this level. This is necessary to reset the level boundaries and allow the horizontal underflow trick to work.
[0:09] Adding to the list of strange tricks I use in this run, if you release Knuckles' glide at a certain height above the ground, he just... dies. No idea what causes this. If I miss it, I just get crushed by the wall, which only takes a few extra seconds.
[0:07] The clock stopped at 9, and restarted at 7. Therefore, two added seconds.
[0:27] All you have to do is jump to get through this ramp - the glide isn't part of it, it's just to fall faster. I screwed up and glided too early on this occasion.
[0:30] Alright, this one is new. I've known that it existed for a while, but it's kind of tricky to execute. Spindashing against the underside of this ramp pushes you into the floor, once you're far enough in zip left. Once you breach the left edge, you start falling, wait about half a second and jump and glide - if you miss you have no chance and you have to reset. Now you're holding a wall facing left, glide over to the right and wait til you hear the sound that indicates Knuckles has grabbed the wall, and hold up.
[0:45] Here the water level changes to the height of the boss room - if you're underwater you get a much higher jump off a wall, so jump off the wall as soon as you see it change. This should make it to the boss room.
[0:56] Fun with hitboxes! The hitbox for standing on the whirlpool is actually slightly larger than the hitbox of the spinning blades. If you stand right on the edge like this you can dodge the blades and easily bounce on Eggrobo for eight hits.

Marble Garden 1 - 1:33 [+0:27]
Why is this level so much slower? Oh, you'll see... you'll see.
[0:13] I hate this ramp with Knuckles. SO MUCH.
[0:36] And I hate this ramp with anyone! Even more!
[0:55] OK, I'm about to set up probably the most nonsensical trick in the entire run. Here I do a screen wrap and jump into the muck pit, removing the object that kills you from the screen and letting me drop into a wall to zip past the boss before it comes back into range.
[1:02] This is actually the loopback of this act, so I'm falling through the start of act 1 again. With no sprites.
[1:11] So, I jump in this pit, and duck, which makes the camera lock onto a boss... but not the boss of this act, the boss of the next one! I spend this entire fight stuck in a wall - to beat the boss I have to spindash to both attack and change my horizontal position. If I change my vertical position, either by jumping, or getting hit, the screen locks in a different position from which I can't attack the boss any more. So, in order to get all those hits in at the start, I have to spindash a number of times. The 6th spindash gets the first hit, then I make two more spindashes, and HOLD the 8th one until I hear it get the second hit, then release and hold one more, which gets three more hits. If I don't do nine spindashes I'm not far enough across and the drill (which you can't see) will hit me, ending the run.
[1:27] So, after getting all those hits, I release the spindash and hold right to push me to the left edge. I can actually get hit after hit 6 without penalty because there's an object directly above my position on the left edge of the screen which means I don't get pushed upwards when I take damage. Then I tap left hoping to get into a good position for the remaining two hits.
[1:33] But, it's still not over! I can kind of see Knuckles' silhouette when the capsule moves past me, so I know when to jump and hit it. But that's not the end of the story. For some reason, hitting the capsule isn't the trigger for the end-level music to play... or at least, not the only one. Tails has to be on screen as well. And it just so happens that pushing the screen to the higher position causes Tails to spawn! So I have to jump to make it change. However, I have to do so from a specific place - it's possible for you to jump into positions where Knuckles doesn't land on the ground (and is stuck forever, not triggering the end of the stage) or is crushed by a spiked crusher that appears on this screen. I'm using the fact that the Flickies from the capsule kind of follow me around to line myself up, then jump in the safe location. Then you get to see the greatest end-stage screen ever.

Marble Garden 2 - 0:03 [-1:02]
So, because I beat act 2's boss, the game plays the little cutscene that plays after that boss (where the background gets progressively darker) and then takes me to Carnival Night! Even though this part isn't normally timed, the timer is running so it counts as part of my time.
Now, as if that wasn't crazy enough, the implications of this glitch are massive. There is a video on Youtube where, on an emulator, you can trick this very same boss into appearing in -Hydrocity 1-: http://www.youtube.com/watch?v=YdSOLalEs7Q
Beating the boss causes the game to try and play the aforementioned cutscene with the Hydrocity sprite set... and then sends you to Carnival Night 1. Therefore, causing the wrong boss to appear could allow us to skip -entire stages-.
This particular glitch is both emulator-only and debug-only - attempting the same method on an actual cart will cause a hard reset. But if it can be found to be useful anywhere, it would be an absolutely incredible development.

Carnival Night 1 - 0:57 [-0:01]
[0:35] This superglide is new. Probably only saves a second or two, but gains loads of style points.
[0:44] The spinning top is limited in its movement to the confines of the screen, so by ducking here, I can make it move where I want it to. Then each hit is positioned carefully (relative to the ground) so that I get the attack pattern I want.

Carnival Night 2 - 0:41 [-0:03]
[0:02] A bit too overzealous on my jumps here.
[0:05] This one is new as well - this saves me running up the top, through the bumpers and back down to this area that I am just going to run straight into. Saves maybe three seconds.
[0:22] Got a good bounce here and was able to keep my glide going all the way to the end!
[0:32] If you jump after the boosters and hold nothing, you'll be lined up perfectly so that you fall between those two 10 ring boxes.

Ice Cap 1 - 1:05 [-0:13]
[0:14] For the glitch I'm about to set up, it is vitally important that I don't break the ice wall up ahead.
[0:18] I pause on the ice block to make sure I time pushing right at the right time. I think this was actually a bit high, so I wait a few frames after unpausing to press right. Now when I reach the ice wall I am effectively inside the wall and standing on the ice pillar just as the block destroys it, granting me the very peculiar slope glitch. This effect is (most commonly) created by standing on a sprite (in this case, the ice wall) just as it gets destroyed. Once the object is destroyed, collision detection is completely broken. Whatever angle ground I run on, I will maintain that angle, even if that angle happens to take me straight into a wall! Adding to the fun is that Ice Cap is one of the vertically wrapping levels, which means I can fall forever and not die!
[0:23] I hold right for about half a second in this wall, but besides that it's pretty much all holding left. Now I collect a ring from this set of ten - the amount of rings you picked up lets you know what kind of angle you're at, and determines what you do next. I have 4 rings when I start the glitch, and I can have anywhere between 4 and 8 once I've passed them. I have a different strategy for each, but the relevant one is 5.
If you have 4: there's a huge range of angles you can be at if you miss all the rings, just mess around and hope. I tend to use the same method as I do for 6, and it works sometimes. Note, however, that if you switch to holding right before you go past the two huge crushing blocks, it's very likely that they will crush you as you go past them.
5: This one's easy. After you go past the two huge crushers the screen scrolls into an open area with a left facing slope. As you come through this area your character will appear on the screen for a split second, switch to holding right at this point. Once you get near the end switch back to left otherwise you'll hit an ice blaster which will stop you in an area where you can't get to the boss hallway (without breaking the glitch, anyway).
6: Switch to right when you go past the crushing blocks instead. This one's far less reliable than 5.
7/8: Hold left the whole way down and pray. 7 is more reliable than 8.
[0:31] Now I jump out at the end of the stage. I can break the ice wall from the side, but if I stand on the bridge up ahead the glitch will be cancelled. Interestingly, once you move into this corridor you're actually in what the game internally treats as act 2, which means that if I can get into a wall, I can zip right to the end of the stage. Conveniently, I can. This ground is slightly uneven so I just jump on the slightly raised section of ground - I screwed this up a couple of times, but eventually I run into the wall and zip right to the end of act 2.
[0:40] You can do this glitch from either Sonic's or Knuckles' corridor. In this case, I used Knuckles', but depending which one you end up at you make it to the boss room as follows:
Sonic's corridor: Hold left for two seconds (use the timer) to change your position in the wall, then right for one second to zip to the end of it, then switch back to left until you can jump. Now you're in a sloped tunnel, so hold right and keep jumping until you reach the bottom. If it worked right, you'll appear above the boss room and you'll be standing on thin air. You need to jump down to trigger the boss.
Knuckles's corridor: Hold right for about a second, this pushes you lower in the wall you're stuck in so you can jump. As you see the screen scroll past the final corridor to the boss room, hold left and jump, and you should appear just above the ground.

Ice Cap 2 - 0:00 [-1:17]
Again, the timer restarts here, but there's no time for it to tick over to one second.

Launch Base 1 - 0:54 [-1:27]
[0:09] This has been known for a while with two players, but the method to do it with one player was discovered at the beginning of 2011 by flyingfox. I wait until the moment the timer strikes 9 to move onto the tube because it means I know within a pretty small margin of error where the flybot is going to be at any given time. If you do this too early the flybot will be too far off the top of the screen when you jump down and it will disappear, if you do it too late it'll simply fly into you from the side.
The flybot's pattern is basically this: Imagine a 45 degree line extended from the flybot's position towards the ground and in your direction. If you're on the side of that line that is closer to horizontal, the flybot will simply chase you horizontally, and slowly line itself up with you vertically as well. If you're closer to vertical, the flybot will dive at you at a 45 degree angle until it goes past you vertically, at which point it moves back up at 45 degrees to the height from which it dived. So, in essence, the timing, my position on the tube, and the time I jump off the tube, is all designed to make the flybot behave in exactly the same way, every time.
[0:20] The area I just zipped to looks like this: http://i918.photobucket.com/albums/ad21/mike89sda/LB1loopback.png
In order to reach the boss room from here I have to do nothing more than duck. This part is just slightly too high and you can't really move around in here.
[0:31] I've never beaten this boss as Knuckles without taking a hit (at least not in a speedrun setting), so I pick up the rings available to me here. This boss is much harder as Knuckles because the two bosses remain spaced out like this for the entire fight, whereas as Sonic or Tails the game thinks there's only one boss and they both attack you from the same position.

Launch Base 2 - 2:21 [-0:04]
[0:29] I don't think I did this in my last run, I think I waited a bit longer on this pulley. But yeah, this works, and it saves a bit of time.
[0:45] This is just about my favourite jump in the entire game. Made it even better by gliding at just the right moment and stopping myself at the right edge of that platform!
[0:59] There's actually a very interesting alternate route here. The rotating elevators are positioned so Knuckles can't jump into them, but by luring that flybot into position, you can superglide off it and get in that way. That takes you up to Sonic's boss, which you also can't reach in normal circumstances, you have to do a jump on a precise frame to get the height to reach it. But it's after you beat that boss that things get really interesting... when you come through here as Sonic the timer stops after the first fight and restarts before the second. However, if you come through here as Knuckles, the trigger to restart the timer does not exist! So you fight both of Knuckles' bosses without adding any time to the timer. I asked Breakdown and Mike about the legitimacy of this strategy and they both said that they would time the last two bosses manually, which made it the undoubtedly slower option, which is why you don't see it in this run.
[2:01] I completely screwed this up, you're supposed to be able to get two hits here - once on the way down and once when he bounces back up. Instead I did the first one late and got neither. This costs me two passes later on, or about ten seconds.

End of Sonic 3: 11:04 [-4:01!]

Mushroom Hill 1 - 1:14 [0:00]
[0:22] Got screwed here with the ramp not letting me run up it. Kinda just had to wing it to come up with another decently fast way up.

Mushroom Hill 2 - 1:10 [-0:09]
[0:43] It's faster to climb up here than to take the pulleys, even with Knuckles who can use them faster.
[0:55] I used to have a really risky strategy for six hits here, but now I just do this instead. If you intentionally get hit here you can just stand inside the boss and get six hits before it moves. Because getting hits are so slow in the gauntlet this is still faster than just safely getting five.

Flying Battery 1 - 1:58 [-0:05]
As I mentioned earlier, this level has an instance of the universal timer colliding with the camera timer, so it's actually in my best interest to do the first 30 seconds a bit slower than usual.
[0:24] Specifically, I want to hit this zipline at about 24 and a half. That will ensure that everything is lined up nicely later on.
[1:17] This jump over the spike here is really, really dumb. If you don't get it though, you almost certainly miss out on a cycle of the bombs just up ahead.
[1:32] Landing directly on the boss capsule like this causes a rather amusing music glitch. Also, the hit was entirely intentional.

Flying Battery 2 - 1:34 +31 [-0:24]
This is the reason I'm not really happy with this run. I need to die once to reset the level boundaries, much like Hydrocity 2, but I died a second time trying to activate the zip. The timing is incredibly difficult: based on the testing I've done and videos I've pored over frame-by-frame, there's only one frame where you can jump off the hook and have the trick work. Once you've hit that one frame, you then have to glide exactly two frames later to be stuck in the wall like this. On the life where I died I glided the very next frame and simply fell through.
[0:19] The zip itself is far from trivial. I have to line myself up (watch the three bars underneath the ramp on the left edge of the screen), spindash, hold right and then hold down exactly 14 or 15 frames later. A few times I held down too early which results in you just being stuck in the wall. On the other hand, if you hold down too late, the spring pushes you out which means you have to go back and do the first part again as well. So I much preferred missing early to missing late.
[0:33] The zip pushes you up above this loop. From here all you have to do is hold right, and the game throws you into the boss room. As soon as the camera crosses the x-position where the bridge starts rising, it starts rising - triggering the laser fight is entirely unnecessary.
[1:30] With Knuckles this boss only rotates twice in a cycle, so hitting him three times in the middle and twice on each way up, as you normally would, means you have to wait for a second pass to kill him. By taking a hit here you're able to accurately position yourself between the spikes and the flames and spindash for the remaining hits, which gives you three hits for each time he goes up.

Sandopolis 1 - 2:03 [0:00]
[0:07] I half-heartedly went for a glitch here that would save about 45 seconds if I could hit it first go. If you let go of this glide at exactly the right time, Knuckles can get embedded above the loop, and you can spindash-zip and breach the left edge much like Tails can. It's not the easiest thing in the world to do, but after I did this run I played around with it a bit and found out that I could do it at a reasonable level of accuracy if I pause buffered it. And you get two attempts at it, so I'll definitely throw this into a future run, if I do another one.
[0:39] I actually would have had time to do this pretty comfortably if I'd just spindashed after climbing up this wall. Instead I got there slightly too late and the spikes knocked me backwards. Due to how much of this level is dependent on these timed objects, I lost five seconds to this.

Sandopolis 2 - 2:33 [-0:42]
[0:17] I threw a few screen wraps into the route, which basically let you skip any of these doors you want. This one probably saves about two seconds.
[0:34] If I do a full size jump from flat ground and hold left all the way down, I will always fall through this floor down to the level below.
[1:07] Another screenwrap that saves a couple of seconds just in going up to the block and pushing it.
[1:24] This is the biggest one, saving close to 30 seconds by itself. It has one really weird property, though: if you hit either of the sand fall switches on the way up, instead of letting you do the zip at the end, the game just kills you. So Sonic alone can't do it, but S+T can. All it is is jumping just as the screen comes back to normal, and having the door push me into the wall. After that there's a gap, so I have to glide just as the screen rectifies itself to land on the flat ground past the gap. Then I spindash, jump over something, and I can zip from here.
[2:07] Knuckles isn't supposed to be able to go up this way, but with a perfect spindash from this bottom ramp here you can just make it. Took me two attempts though.
[2:23] It's possible to do this boss in two rounds - what's meant to happen is that instead of bouncing back, Knuckles will just drop into Eggrobo's hitbox and you can get four hits before it closes up. This still didn't work out too badly though.

Lava Reef 1 - 1:33 [-0:13]
[0:37] This is something new I came up with for handling this part, because normally I'd spindash straight into the spikeball, and have one or zero rings for the next part, which in my opinion is comfortably the hardest platforming in the run. So in order to preserve my rings I glided to stop here, and then spindash jumped over it. Probably about even time wise, but much safer.
[1:33] This fire shield is absolutely essential for the next stage. You could get the one in act 2, but this one is free, so why not take it?

Lava Reef 2 - 1:34 [-0:01]
[0:46] This is really annoying, because if you frame-by-frame it I am well within the button's sprite by the time I glide away, but it still didn't count somehow. I guess the lesson to learn is you have to listen for the sound rather than rely on your eyes.

Hidden Palace - 0:09 [0:00]
Didn't get 8 - reset!

Sky Sanctuary - 1:05 [-0:09]
Somehow I always play really badly on this stage on my submitted runs :(
[0:26] Somehow failed to spindash here which compounded the losses from getting the worst possible pattern. At least the second boss gave me the best possible pattern to make up for it!

This run is probably the most difficult that I've ever attempted, containing a plethora of ridiculous tricks from start to finish. It's for that reason that I submitted this, even though I know there's a lot left on the table. To anyone who wishes to beat it, I wish you the very best of luck.

Enjoy the run!

Thanks go out to:
mikwuyma, Breakdown, dex, Flip, VorpalEdge - the SDA crew, keeping things awesome!
Nate - for his capture and encoding genius, none of which is present in this run :(

Well, well, this has been a long time coming indeed. Originally I was planning to submit a Tails run with my Sonic and Knuckles runs back in 2006, but at the time I thought one certain trick was too difficult and the result would be too sloppy anyway, since Tails loses a good few seconds every time you go to spindash and fly instead... and I was doing that a lot.

Now, I have a real Genesis, real carts and a real controller, and that trick is one of the easier ones in the game! I'd like to think I acquitted myself well on the rest of the run too.

This next part is going to be part of all my submissions for this game, so if you've already read it, skip it and go straight to the run analysis.

* Horizontal Underflow Glitch
At the start of any given level, you can try and go left right at the start, but of course the game won't let you, there's a hard lock there. However, because the game performs collision checks every frame, if you were able to move fast enough you could bypass the lock on the start of the stage and go "behind" the left edge of the stage. In memory, the game treats your x-coordinate as less than 0... which, being an unsigned integer, increases it to the maximum allowed by the map - 32767. This sends you to the aforementioned loopback area. Now the camera scrolls as fast as it can to the right trying to find you. The camera will stop scrolling under one of two conditions: either the game finds you, or it encounters a boss. Therefore, in any level which permits this, it is possible to skip from the left side of the level right to the boss!
Now before you start asking why I don't do this on every stage, remember that I mentioned you need a lot of speed to get through the left hand side. There's a few ways of doing it depending on the circumstances, but the most common is being ejected from a wall. That requires getting stuck in a wall in the first place, which requires some very select circumstances depending on the level. In the Tails run, it is used in... Hydrocity 2, Marble Garden 2, Carnival Night 1, Ice Cap 2, Launch Base 1, Sandopolis 1, and Lava Reef 2. Plus there's one in Mushroom Hill 1 that I don't use. Yikes!

* Wall Ejection
Once inside a wall, holding left sends you right, and holding right sends you left. Easy!

With that in mind, hopefully some of the decisions in the run will make more sense. On to it, then!

Angel Island 1 [0:50]
[0:03] New route already! I go up the top and take the speed shoes along the top route, it saves about three seconds over the bottom route.

Angel Island 2 [1:30]
[0:09] I stop and charge this spindash a bit longer than usual because the upcoming gap is really finicky about whether it lets you over or not
[0:15] Another route change, one I'd never have considered if not for watching HDL's streams of the game. This route is actually faster by about four seconds... assuming neither of the stupid vines get in your way.
[1:30] And a nice little graphical glitch at the end.

Hydrocity 1 [0:41]
[0:12] Landing on this loop, spindashing and flying off causes a really strange effect. Normally you lose almost all your speed when you fly upwards, but when you're above the top of the screen this rule doesn't apply... so I keep my spindash speed practically all the way to the end of the stage!
[0:27] Then I'm counting the green blocks across the top of this wall. After the 8th one I jump off and line myself up so I land on the loop with the invincibility.
[0:35] I take one free hit here because I can get five guaranteed from underneath the boss once it appears on the screen, which means I can kill the boss in one round. This saves about two seconds over just hovering at the top.
[0:41] Also, the music glitch here is pretty funny.

Hydrocity 2 [0:34 +7]
[0:12] Tails must die to reset the level boundaries. In this run seven seconds are added.
[0:09] This jump is much easier with Tails than with Sonic, since you get to chances to readjust your height (both the jump itself and the fly), whereas Sonic only gets one. It also helps that Tails has a smaller hitbox which is less prone to crushing deaths in this area. The basic gist of it is that you need to be moving right (hence the insta-shield) at a speed slower than the wall is moving (which is why this doesn't work as Knuckles - even if it did, he has to reach a completely different boss area). At the height of your jump and fly, Tails is slightly embedded in the wall, and the game, not knowing what to do, ejects you downwards into the floor.
[0:11] The loopback area in Hydrocity 2 looks like this: http://i918.photobucket.com/albums/ad21/mike89sda/HC2loopback.png
You can't see it in this screenshot, but there's a massive hill on the left. So basically, since the boss room is much higher than this, you need to spindash up the hill, then just hold your jump for as long as you can. You have a massive range of y-coordinates for which this will work (you practically have right up to the top of the screen available to you).
[0:26] One of the more famous music glitches in the game, if you start the drowning timer and then jump out the miniboss music starts playing instead of the main boss music. Then I launch into the boss strategy, which is four flying hits before the blades start spinning, and then four bouncing hits before the blades get high enough to hit you. I completely botched it in this run, only got 3 and 2... and somehow landed on the safe part of the whirlpool. I have no idea how I did it, but I'll take it.

Marble Garden 1 [0:57]
[0:12] Missed the hole in the ceiling, it's quicker from this position to just land on the spikes and have them send you up.
[0:29] I BEAT THE RAMP OF DOOM YESSSSS. For some reason this ramp really likes stopping you dead at the bottom. It really, really likes doing this to Tails... probably happened 75% of the time. Going up the ramp and getting the jump at the end of it saves around four seconds over being stopped.
[0:57] Grabbing the fire shield here for a bit of help on the next boss.

Marble Garden 2 [0:50]
[0:13] So I was wrong, and Tails can come to a dead stop on these ramps. All you have to do is make sure you keep trying to run up the ramp, don't let go of everything otherwise you'll just roll. This makes the level a lot less random... I used to set this up off the platform up above which is a total crapshoot.
[0:19] The loopback area that I've just zipped to looks like this: http://i918.photobucket.com/albums/ad21/mike89sda/MG2loopback.png
And in that position, you're only just too low to line up with the boss map! So all I have to do is spindash to the left, but not so fast as to go over the hill and end up on the other side. A two tap spindash works wonders: if you see the top half of the signpost at the bottom of the screen as the camera flies past, you're in the right place. The spindash didn't work the first time, I just got stopped by the ramp... so just spindash again.
[0:33] This is the worse of the two patterns that are possible here, but both are still easy two-rounds.

Carnival Night 1 [0:57]
You thought the game was broken already? Hahaha you ain't seen nothing yet.
[0:09] What I just did here is make the game think I'm standing on the pinwheel I just touched. Standing on the pinwheels makes two very interesting changes to the game's physics: a) the effect of gravity is -greatly- increased, and b) it can be applied in any direction. In practice, what this means is I can make gravity apply to the left and, you guessed it, go straight to the boss room.
[0:10] OK, first, I have to do a two-tap spindash out of this ramp, wait for the spikes to retract into the ground and then release, then hold left so I don't overshoot this platform. Running into the spikes up ahead is actually incredibly important, because it lines me up perfectly and ensures this trick works 100% of the time. Sometimes if you wait a bit longer and don't hit the spikes, which you would think would be faster, Tails will just fall off the platform and run along the ceiling instead of running around it.
[0:15] Once I get past the monitors I have to spindash in mid-air (yes, really! These are pretty easy, it's like spindashing off a steep slope like in MG2) twice to activate the horizontal underflow.
[0:18] The loopback area you get taken to in this level looks like this: http://i918.photobucket.com/albums/ad21/mike89sda/CN1loopback.png
Basically I'm now up against that wall there. In order to get high enough to reach the boss room while keeping the glitch, I have to spindash a further two times up this wall. How you do the spindashes are exactly the same, so it's not as hard as it sounds, but missing the spindash is run-ending, because of the glitches coming up later.
[0:27] Now I have to fight this boss without jumping too... the method I use to land on the spinning top is my brother's, just hold left until it hits the bottom the second time and then roll down, works every time. Then it's just roll off the spinning top and bounce on the boss until you get all the remaining hits. This doesn't cause me to fall super fast... presumably because I'm rolling off a sprite, much like how running off the ring boxes at the start didn't cause me to fall super fast either.
[0:57] This is just a bit of fun, if you spindash just before the results screen comes up, and hold down when you get control back, the screen scrolls down straight away instead of waiting like it normally does.

Carnival Night 2 [0:46]
[0:05] OK, so I know some of you will be asking, why can I jump off that barrel? Well I don't know the answer for sure, but I'm guessing that the barrel makes its own modifications to the physics, basically consisting of "you can't move unless you jump" that overrides the part that says "if you jump you lose these effects" from the wheel.
[0:10] I hold left as I touch the corner here, and the game gets really confused and just sends me straight up to the ceiling. Your guess is as good as mine as to why this happens.
[0:16] OK, remember when I said that when you are above the top of the screen, you're interacting with stuff on the bottom? Well if you've ever played around with debug and gone to the bottom of Carnival Night 2, you see there's all these platforms spaced evenly apart. So what I'm doing is slowly walking up the side of one of them and then falling to the right, and trying to regulate my speed so that I stay in between two lines of platforms. Then once I see open area I jump out and spindash to the boss!

Ice Cap 1 [1:14]
[0:20] I pause on the ice block to make sure I time pushing right at the right time. You want Tails' head to be just below the spikes. If you do it right you are slightly inside the wall and standing on the ice pillar just as the block destroys it, granting you the very peculiar slope glitch. This is a really strange state where Tails doesn't interact with the ground properly. Basically Tails takes on the angle of whatever ground he's running on. Even if that takes him right across thin air or into a wall! What tends to cause the slope glitch to occur is standing on a sprite as it gets destroyed - what timing this run does is actually causes Tails to be slightly embedded in the wall at the time the platform crashes into the sprite wall.
[0:22] Now, once I activate the slope glitch I neutral jump onto the left facing slope, jump off it onto the right facing slope and press down, then hold left. I get pushed into a wall, switch to holding right for roughly half of the length of the wall, then switch back to left. Now I start falling infinitely - Ice Cap 1 has no kill plane so I can literally fall forever - and I pick up a single ring from the set of ten. Depending on how many rings I pick up through here I have different strategies, as follows:
4 rings after going past: there's a huge range of angles you can be at if you miss all the rings, just mess around and hope. I tend to use the same method as I do for 6, and it works sometimes. Note, however, that if you switch to holding right before you go past the two huge crushing blocks, it's very likely that they will crush you as you go past them.
5: This one's easy. After you go past the two huge crushers the screen scrolls into an open area with a left facing slope. As you come through this area your character will appear on the screen for a split second, switch to holding right at this point. Once you get near the end switch back to left otherwise you'll hit an ice blaster which will stop you in an area where you can't get to the boss hallway (without breaking the glitch, anyway).
6: Switch to right when you go past the crushing blocks instead. This one's far less reliable than 5.
7/8: Hold left the whole way down and pray. 7 is more reliable than 8.
Now, the chart above is for Sonic and Knuckles, who have slightly larger hitboxes than Tails. However I haven't noticed the differences to be too significant so I use the same methodology for all three characters. In this case I got 5 which I'm happiest with, I find the method I use there to be the most consistent.
[0:33] As Tails, I jump out once I see this elevator platform here. You can take it further but if you go too far, once you enter the hallway at the end, you're actually in act 2 (which is about to become important in a second), and once you're in act 2 there's a kill plane and you'll just die. Other things you can do include being stuck inside the wall above this area and being stuck on top of spikes (which kills the glitch) or worse, glitching into Knuckles' path and landing on the bridge, which also kills the glitch. This is a few seconds slower than getting it perfect (into either hallway), but this glitch is already a serious run-ender, I don't need more reasons to make it so.
[0:45] Now I have to run into a right facing slope to drop into the ground and activate the act 2 zip... which I failed at once, but I got it the next time. If you leave the jumping out of the roll later, it's possible to do this and not know which corridor you're in: if the first thing you see of the screen scrolling is a checkpoint, you're at Sonic's corridor, if it's a switch, you're in Knuckles's corridor. Which one you're at determines how you get to the act 2 boss room:
Sonic's corridor: Hold left for two seconds (use the timer) to change your position in the wall, then right for one second to zip to the end of it, then switch back to left until you can jump. Now you're in a sloped tunnel, so hold right and keep jumping until you reach the bottom. If it worked right, you'll appear above the boss room and you'll be standing on thin air. You need to jump down to trigger the boss.
Knuckles's corridor: Hold right for about a second, this pushes you lower in the wall you're stuck in so you can jump. As you see the screen scroll past the final corridor to the boss room, hold left and jump, and you should appear just above the ground.
Obviously in this case I knew I was in Sonic's corridor, so I performed the first method.
[1:04] This boss can go a little bit faster... if I land this jump on the slope and jump just before I hit the right wall, I can bounce on Robotnik for all eight hits. I've never actually done it though, and it saves no more than five seconds, so I'm not too mad about missing it.

Ice Cap 2 [0:00]
Blink and you'll miss it! It's actually important for this spindash to be timed well because the timer is running here, and I think it takes 56 frames in the best case, so it's easy to miss it and get one second.

Launch Base 1 [1:02]
This is probably the simplest level in the game, short of Hidden Palace I guess, so it makes me really mad that I screwed it up so badly here. Also, I need to give flyingfox her due by pointing out that this is in fact her discovery.
[0:08] I wait until the moment the timer strikes 8 to move onto the tube because it means I know within a pretty small margin of error where the flybot is going to be at any given time. If you do this too early the flybot will be too far off the top of the screen when you jump down and it will disappear, if you do it too late it'll simply fly into you from the side.
The flybot's pattern is basically this: Imagine a 45 degree line extended from the flybot's position towards the ground and in your direction. If you're on the side of that line that is closer to horizontal, the flybot will simply chase you horizontally, and slowly line itself up with you vertically as well. If you're closer to vertical, the flybot will dive at you at a 45 degree angle until it goes past you vertically, at which point it moves back up at 45 degrees to the height from which it dived. So, in essence, the timing, my position on the tube, and the time I jump off the tube, is all designed to make the flybot behave in exactly the same way, every time.
[0:17] However, I obviously jumped off either a bit too early or too late, because the flybot was a bit higher than usual, and instead of knocking me into the spikes, knocked me in the other direction. At this point I'd already decided that I wasn't going to let a run that had got past Ice Cap go lightly, so I went to my backup plan: You can do this from the other side, but it's a bit trickier and definitely slower.
[0:29] In an incredible piece of good fortune, I picked up the ring that hit forced me to drop. The fact that this was fortunate was another mistake of mine, because you should never get hit on this boss.
[0:30] The area I just zipped to looks like this: http://i918.photobucket.com/albums/ad21/mike89sda/LB1loopback.png
In order to reach the boss room from here I have to do nothing more than duck. This part is just slightly too high and you can't really move around in here.
[1:02] No added time is accrued for this death because the timer doesn't start up by the time you die.

Launch Base 2 [1:38]
[0:21] This hit was meant to knock me the other way, whatever. Once I hit the bottom level though, spindashing is actually a bad idea because if you're going faster than a certain speed the booster ahead just plain doesn't work.
[0:33] This is a really tricky fly; the aim is to basically start the fly the instant you hit the ceiling so you carry your spindash speed through the descent. Not the easiest thing in the world, I'd missed it enough times this way to work out what to do to recover it as neatly as possible.
[0:49] Route change! I grab the invincibility, not really for the orbinauts up ahead, but for the flybot around the two elevators later. I think it saves about a second.
[1:07] A potential improvement here is if you fly up at the top of this screen in just the right way, you can bypass the invisible wall that stops you from hitting Robotnik's machine and kill it before Robotnik even appears. However, it takes a little bit to set up and then fall from the fly, and if you screw it up you can be stuck on top of the invisible wall with no escape. See my earlier rule about runs that made it past Ice Cap.
[1:18] But this method is still pretty cool. :D

Mushroom Hill 1 [1:08]
This is the one level with a known better route that I intentionally do not attempt. It's possible to make the door to the first Special Stage push you into the floor and zip to the end of the stage, but I've never seen anyone do it without extensive pause buffering, because if you miss an input by one or two frames, you just die. Now I don't have anything against pause buffering in general, I'm just incredibly bad at making it work for me.
[0:24] This is a really cool trick, taking speed shoes on the upper route. Tails has a much harder time of this than Sonic because Sonic can insta-shield which greatly increases his hitbox so he doesn't have to move as far out of the way. If you mistime it as Tails you can catch the edge which means you have to spend a couple of precious seconds flying back up.

Mushroom Hill 2 [1:12]
[0:10] If you jump on the exact frame you regain control here, you can actually jump out of mid-air and fly up to the red spring that I'm about to fly up to the slower way. It's about two seconds faster if you hit it, but it's just blind luck.
[0:32] This is just unlucky, sometimes you get hit like this and sometimes you get through. It doesn't matter since I'm going to pick up a shield before the boss anyway... only to lose it again.
[0:58] I take a hit here so Tails can get six hits on this boss before he moves, and only needs two in the gauntlet where hits are much slower.

Flying Battery 1 [1:33]
[0:20] This is the Leap of Faith, my favourite trick in the entire game, owing to it being one of very few that I found myself, and also not being dependent on some programming error. When I first spotted that this might be possible by looking at the map of the stage I kept coming close but never making it, and then stumbled upon a neat property of Tails' flight. As you ascend, Tails decelerates, and accelerates as he falls. However, you can cancel that deceleration by flying into a ceiling! So that makes you travel faster on average than just flying in the middle of nowhere, and gives you just enough time to get out. The hardest part is the first fly: you have to make sure you stay quite close to the ceiling without going too high. I find that hitting four buttons in the air puts you at a good height to make it to the other side around 90% of the time.
[0:44] Time for random bullshit hour! Sometimes ramps will just stop you like this for no good reason, the first one underwater in Launch Base 2 is particularly notorious for it.
[1:33] After the boss delivers the last hit to itself, there's a couple of seconds where you can stand on the corner of this capsule before it gets destroyed. Once it gets destroyed it's replaced with a different sprite, and that triggers the slope glitch to occur again. I'm going to carry this through to act 2 and completely ignore the fact that it exists.

Flying Battery 2 [1:25]
[0:04] Remembering that I can't touch any sprites or I cancel this glitch, I have to ignore the zipline at the bottom, this entire mesh cylinder, and the spring just above it. It makes the start a bit slow, but it's more than worth it to skip the rest.
[0:16] Right, this is the last, and strangest of the zips done with slope glitch. When you aim at this angle and hold nothing, Tails goes into the wall and gets sent downwards, and then right up to the top. Tails' speed must be regulated here because you have to be right at the top of the screen for the end of the act; if you are too low, you simply die.

Sandopolis 1 [1:12]
The time on this level basically comes completely down to luck... I haven't been able to find with certainty a spot that will always initiate this zip properly, half the time you seem to just get stuck.
[1:12] Again, wasting some time on the boss map here where it doesn't count against me. The good time here is 1:14 so I'm aiming to waste two seconds here.

Sandopolis 2 [2:24]
[0:15] Sandopolis 2 is one of the vertical wrapping levels, and I'm going to abuse this fact to skip a number of doors that I'd have to otherwise slowly push switches to open. Here's the first.
[0:31] A full height jump from this platform, holding left the whole way down, always causes you to just clip through this part of the ground.
[1:04] Here's the second door skip. Note the slope that I'm standing on isn't properly loaded for some reason... if you take this off the screen and come back it will be a slope like it should be.
[1:17] And the third and final one. Once I get pushed into the wall I have to fly to make sure I land on some solid ground here, then hope that the moving platform in front of me isn't at its lowest point (which blocks me, and could crush me if its timing is really bad). At 1:24 I jump over a little step into a wall, and zip to the right. This zip is really strange because if you activate either of the sand falls, no matter if they're nowhere near you, attempting the zip will cause you to die.

Lava Reef 1 [1:48]
[0:15] I haven't hit this zip in -years-! It seems entirely random to me whether it goes off but basically I do a less-than-full-speed spindash and just hold right, and sometimes I'll sink into the floor and it'll work. This works with any character, by the way. It saves something like 9 seconds over going around the normal way.
[0:38] This level's difficult trick: I'm attempting to jump through a stair. Sonic 3's collision detection is kinda wonky; the game lets you pass through corners if it thinks you're just going to continue on in your chosen direction - I think this is actually intentional, to keep the speed of the game up. So the trick here is to do a spindash jump such that the game thinks I'm going to pass over the top of the corner, and then don't. This requires frame-precise jump height, so taking four attempts isn't too bad here.
[1:48] Another quick pause makes sure I have the next glitch lined up properly.

Lava Reef 2 [0:38]
This time is absolutely ridiculous if you have ever played this game. I manage to skip both the minute-long stage and the two-minute-long boss with great efficiency.
[0:06] This level is a bit bizarre in how the zip works. In most cases even if it only takes a few seconds to initiate a zip that is long enough for the game to load the entire level out in front of you. In this level the game is still loading the level off into the distance by the time you do the zip! At somewhere between 6.7 and 7 seconds, the very right edge of the level that has been loaded corresponds to this platform here: http://i918.photobucket.com/albums/ad21/mike89sda/LR2wrap.png
The screen drops slightly, this is the indicator of a successful zip. If the screen doesn't drop at all you're stuck in the wall before the tube, and if you keep falling you're in the pit on the other side and are about to die.
[0:28] Now the really fun part. I'm going to attempt to break into Knuckles's route, completely bypassing the rocks that only he can break. The way to do this is a series of three very quick spindashes: the first, at the edge of the platform, builds speed. The second spindash tricks the game into thinking you're heading off to the right again, and the camera pushes out that way. If the first spindash was fast enough, the game actually sends the rock completely off screen for a few frames, which gives you just enough time to do a third spindash and go straight through it.
[0:32] And I got it... second go! I've never, ever got it anywhere near this fast before. Now I just have to get out! Getting out is much easier than getting in because the tube gives you all the speed you'll ever need to pull off the last two spindashes.

Hidden Palace [0:31]
All standard fare. Right now I'm a complete nervous wreck because I know this is -the- run after that LR2, so I'm just trying to calm down and take on the last few levels the same as I always would.

Sky Sanctuary [1:13]
Aside from Launch Base 1, this was the only level where I made really ugly mistakes, and I'd say that was just from the nerves.
[0:33] This isn't a remotely hard thing to do... I just occasionally decide that it should be done sooner, not realising the screen isn't all the way down yet. I had serious flashbacks to my old Sonic run from 2006, which failed this four times before finally getting the screen wrap...
I got a ridiculously bad boss pattern too, though I probably should have learned the method where you take a hit before Metal Sonic becomes vulnerable in each cycle. It definitely works out to be an advantage if you get the bad pattern.

Death Egg 1 [1:54]
[0:31] I like having this shield for the boss, just knowing you have one extra hit to play with is so useful, so I was pretty disappointed to go to all the work of dodging the enemy and bullet and then lose the shield anyway.
[1:35] I lost a lot of time around here in particular, when I had to go and chase the solitary ring instead of using my invincibility time to grab hits. The way this fight is supposed to go is that you get the fourth hit, and don't miss it like I did, which makes the boss knock you back to the left for easy hits.
[1:46] This is my new strategy for the second phase: roll off the platform as it rises and try and bounce on it for all eight hits. What makes this difficult is the way the spinning platforms work: if you're on the left hand side of the eye the platforms rotate clockwise, and if you're on the right hand side they rotate anticlockwise. What I'm actually trying to do is constantly switch between being on the left and right hand sides, so that they get so confused that they never have enough momentum to get to the top and hit me. I screwed it up the first time, rolled too early, but got put in an incredibly good spot to recover, and took my chance with both hands.

Death Egg 2 [3:24]
[0:02] I don't think I've ever managed to spindash off this screen too fast before. At least it made dodging the enemy nice and easy, I can't tell you how many runs were wrecked by that bastard.
[0:46] This is a pretty funny glitch, but sideways-facing spikes do no damage under reverse gravity. This trick isn't exclusive to Death Egg, either: you can try it in any stage with Debug mode, you never take damage! I liked doing it with 0 rings, too, thought that was a nice touch.
[3:24] And... it's over!

TOTAL TIME: 29:28

Assuming there's no more major timesavers to be found (a very poor assumption, in my experience), and that the audio problems aren't deemed rejection worthy, I think I can put this category away for good. If someone beats this time, well, bravo, they've earned it.

Enjoy the run!

Single-segment as Sonic and Tails with deaths: 0:30:05 by Mark McKenzie and Mike McKenzie.

mike89's Comments:

Thanks go out to:
The SDA crew (too many of you to list now) - keeping SDA awesome!

werster - obviously, for being the larger half of this run. There's no doubt that if I was playing Sonic we wouldn't have pushed this as far as we did in the end.
HDL - the undisputed best at this game, came up with a lot of strats for us
Sprint, nitsuja, upthorn, marzojr - The TASing crew for this game. nitsuja in particular took the game to a whole new level, and the latter two have built upon his work.
ORKAL - Posted an excellent series of videos on Youtube highlighting just how broken this game really is. I highly recommend you check them out if you're interested in the game.
Everyone who watched in both our streams, you guys are great!

Speedrun history:
25/9/10 - 37:04 - mike89/flyingfox
21/1/13 - 30:05 - werster/mike89

That gap, right there, is the reason for this run in a nutshell. Ever since flyingfox and I completed the 2010 run there's been new TAS developments, new consistent real time methods, for tricks practically on a monthly basis. It should also be noted that the execution in levels is considerably better too, but tricks are worth more of that seven minutes' improvement, by far.

We had about five months to do this run - I returned home from England in September and moved to Queensland in February, so for all of the time between that (minus the two weeks we spent in the USA for AGDQ) we were living together and able to do attempts. I say "able to" because it wasn't always the one thing either of us wanted to do at a particular time, and particularly after bad sessions I would lose motivation to do the run for a week at a time, if not more. At times our consistency suffered for this, but for the most part every session or two there would be one good run amongst all the wreckage.

In the end, it was doing this run at the Spooktacular marathon (surrounded by a bunch of spooky games, lol) that got this going more frequently. The run was an absolute trainwreck, but people absolutely lapped up the interaction! That was also the reason I ended up going to AGDQ'13, I wasn't going to go until then but that tipped me over the edge. So you have my brother to blame for that. :P

This next part is going to be part of all my submissions for this game, so if you've already read it, skip it and go straight to the run analysis.

* Horizontal Underflow Glitch
At the start of any given level, you can try and go left right at the start, but of course the game won't let you, there's a hard lock there. However, because the game performs collision checks every frame, if you were able to move fast enough you could bypass the lock on the start of the stage and go "behind" the left edge of the stage. In memory, the game treats your x-coordinate as less than 0... which, being an unsigned integer, increases it to the maximum allowed by the map - 32767. This sends you to the aforementioned loopback area. Now the camera scrolls as fast as it can to the right trying to find you. The camera will stop scrolling under one of two conditions: either the game finds you, or it encounters a boss. Therefore, in any level which permits this, it is possible to skip from the left side of the level right to the boss!
Now before you start asking why I don't do this on every stage, remember that I mentioned you need a lot of speed to get through the left hand side. There's a few ways of doing it depending on the circumstances, but the most common is being ejected from a wall. That requires getting stuck in a wall in the first place, which requires some very select circumstances depending on the level. In the Sonic and Tails run, it is used in Hydrocity 2, Marble Garden 2, Carnival Night 1, Ice Cap, Launch Base 1, Mushroom Hill 1, Flying Battery 1, and Death Egg 2.

* Wall Ejection
Once inside a wall, holding left sends you right, and holding right sends you left. Easy!

And a couple of things specific to the Sonic/Tails combination:
* Tails Returns!
At times you may notice me (as Tails) stop for seemingly no reason; the purpose for this is to make him reappear at a specific point. Tails has certain "zones" in which he will reappear, and after a certain length of time spent off screen, once Sonic enters a new "zone" he will begin to fall. Additionally, you can make Tails fall even faster by jumping to the same height that Tails is falling at, which returns control to player 2 immediately.

* Tails Phases Through Sprites?
Using a similar methodology to the screen wrap glitch above, if you move Tails off screen he can pass through certain sprites. The same rules apply, except that you only have a limited time because after a few seconds Tails will be treated as being too far off screen and be returned to Sonic's position.

With that in mind, hopefully some of the decisions in the run will make more sense. On to it, then!

In these comments, I'm going to refer specifically to my actions. All of the technical stuff about what Sonic's up to will be in werster's comments... hopefully.

Angel Island 1 (0:48) [-0:03]
So, what's going on at the start of the level is... there's a flag where Sonic doesn't get control until Knuckles disappears off the screen, but there's no such flag for Tails. So Tails can carry Sonic a fair distance into the level before the timer even starts. I actually force Tails to appear slightly sooner than normal by mashing the buttons in the intro.
[0:38] Tails will always respawn here, and if you're lucky he'll drop out of flight and jump out to the left. At this point I take back control and follow Sonic into the miniboss room. If Tails is too far back he'll actually stop at the left edge, which is far from ideal as you have to get all the way across to the tree, stop (in order to make sure you're flying straight up) and then fly up without flying too high, but high enough to reach the miniboss at its highest point. Obviously the tree is my visual cue here; it's far enough away that neither Sonic or Tails will get hit but close enough that Sonic's Insta-Shield will hit the boss.

Angel Island 2 (1:30) [-0:03]
I don't do anything here, but that background music is awesome, right? Right?

Hydrocity 1 (0:47) [-0:04]
[0:00] The trick here is simply to hit A (only once!) and right at pretty much the same time. I use a certain note in the music to time it, which consistently lands us just behind the hand.
[0:33] By a complete miracle I managed to catch myself up while off screen and land in the charging hand here. This lets me go through to the boss and help out getting a couple of hits if necessary.
[0:45] As it turned out, it was necessary, but we chained hits together just about perfectly so he didn't even go up the right hand side!

Hydrocity 2 (0:31 +7) [-0:03]
[0:07] The trick to doing this consistently as Sonic and Tails is that there's actually a consistent height that works for Tails solo. As Tails has more control over his vertical position (by being able to jump and then later fly) we actually use Tails to put Sonic into the ideal position. Unlike the last time I did this category, this method almost never fails.
[0:22] As soon as the boss room appears I start mashing buttons and Tails appears soon after. Once I'm released from flight, I then fly up and get four hits before he comes into Sonic's range, and he gets the other four from below.

Marble Garden 1 (0:55) [-0:05]
[0:04] I stand still here for no other reason than to control when Tails comes back.
[0:23] This is kind of a blind catch, but by default we both move across to the right hand side and hope it works. Normally it does.
[0:46] What's meant to happen here is that I either drop down before we enter the boss room, or during the first couple of hits, I fly upwards and get hit 5, and we one-round the boss without waiting as the old run did. But Tails didn't drop down in time and we only got five hits.

Marble Garden 2 (0:56) [-0:14]
[0:03] I'm actually trying to follow Mark through here... I just accidentally did that stupid one-frame thing where if you jump the same frame you release a spindash, you just go straight up. Now we have to wait for Tails to respawn up the top.
[0:12] Okay, that looked really easy, but in our attempts Tails would miss catching Sonic like 60% of the time and we were never any the wiser as to why. Another really frustrating aspect of running this game. :/
[0:32] Watch for the speed shoes to go off the left hand side of the screen - I start mashing about now in the hope that Tails will respawn in the boss arena. It certainly wasn't 100% consistent, but it worked more often than it didn't. Not this time though!

Carnival Night 1 (0:43) [-0:08]
[0:37] Mark currently has the wheel glitch (where the game thinks he's standing on the wheel) and cannot jump, otherwise the glitch will be broken. However, since he's standing on the left wall he has control over the camera. So he moves the camera into specific positions while I fight the boss, trying to keep the spike on the right hand side of the screen.
[0:43] I also have to collect the lightning shield here. The signpost drops over a white tile on the ground (regardless of where the boss is killed!), you're aiming for the very next white tile to the right.

Carnival Night 2 (1:14) [-1:20]
Now here's where things get fun.
[0:16] One interesting side effect of the wheel glitch is that obviously the game doesn't expect you to be in any other state while also on the wheel. So if Sonic lands on a barrel, or is caught by Tails, as happens here, that overrides the inability to jump (but only while in that state).
[0:46] Strictly speaking flying Sonic up here isn't necessary, but this allows him to maintain wheel glitch all the way through to the boss, which skips the Knuckles cutscene below.
[0:59] Have to do one more setup first, though. This took three tries. The correct positioning is to get quite close to the corner and have Sonic jump from there.

Ice Cap 1 (1:33) [-0:29]
[0:31] As Tails, literally all you have to do is break this block. That completely breaks Sonic's collision detection and causes this to happen.
[1:02] If you can see the eight tall ice blocks as you come through here, Sonic is in Sonic's hallway at the end of the act and the rest is easy.

Ice Cap 2 (0:00) [-1:01]
If you were to get one second here, this would actually count against your time. Thankfully, this did not happen.

Launch Base 1 (0:40) [-0:03]
[0:03] What you want to do here is watch very carefully and jump at the very moment that Tails starts running on flat ground. If you go too late, you get what happened to me at AGDQ where I got caught by the lip. :(
[0:10] Here, just tap A twice and have an idea of where the left edge of the spikes is.

Launch Base 2 (1:28) [-0:16]
[0:37] I was nearly rendered completely useless here, but Mark just missed the double bird bounce. Flying up here saves 20-odd seconds over Sonic's intended route.
[1:10] Here you just have to hold Sonic up in the corner and let him do everything with absolutely no risk.
[1:19] This one's fun. Simply spindash in place as you always would for six hits, then Sonic jumps over and gets the last three.

Mushroom Hill 1 (0:39) [-0:39]
[0:17] As Tails here, my primary objective is to make sure I pick up a ring. This isn't strictly necessary for the boss fight, but it takes a lot of the risk out of it.

Mushroom Hill 2 (1:13) [-0:09]
[0:16] The only place Tails might get called upon to do anything is here - if Mark missed the mushroom jump twice I would fly him up instead.

Flying Battery 1 (1:19) [-0:08]
[0:09] At the start you're kind of at the mercy of how high Tails decides to respawn. The reason Sonic stays up here is if you continue down, Tails will keep slowly floating down and waste many more seconds.
[0:12] Now Tails lifts Sonic onto the monkey bars and all hell breaks loose. Keep your eye on the platform Tails is standing on: right now, Sonic has slope glitch, and that will be cancelled if he touches that platform. It does slowly oscillate up and down, so Sonic has to wait until it's all the way down before exiting the wall. Similarly, as Tails I anticipate this, and start flying about a jump height above where Sonic will be.
[0:34] Flying through this always looks cool. If you don't fly through this trigger, you'll actually start running around the outside of the cylinder instead - and you still have to fly Sonic up to the top.

Flying Battery 2 (1:24) [-0:10]
[0:09] There's a couple of different ways of doing this (you can have Tails fly Sonic up through the cylinder and the next tube, for instance) but this is the method we settled on. Normally Tails would appear from the top and Sonic could line this up by jumping in between the second and third monkey bars, but he appeared from the bottom instead so we reverted to this method.

Sandopolis 1 (2:17) [-0:12]
The hardest part of this stage is making sure Tails catches Sonic. This is surprisingly difficult, as even lining Sonic and Tails up doesn't work all the time!
[0:35] If you catch this cycle with the spike blocks earlier in the stage, at this checkpoint you can simply hold right and jump, and the platform will always be at the far right.
[0:40] And here's the first big flight mistake. I ended up just dropping down and resetting this because I was too high up. Remember, Tails can only fly for 8 seconds consecutively before falling to the ground.
[2:15] Either character can do this last hit, but in the interest of playing it safe I did it. Once the golem lands from the previous jump, wait two and a half seconds (use the timer!) and then take the hit. This means you'll both be invincible and have enough time to get into position for the final hit.

Sandopolis 2 (2:46) [+0:01]
[0:04] This is a tricky jump for Tails, but you want to jump underneath the light switch so that he starts pushing the door open while Sonic turns the lights on.
[0:26] Sometimes Tails will spawn up here, and in those cases he would push the door open while Sonic continued ahead.
[0:55] Take great care not to get left behind here as Tails! If Sonic is stuck here alone, Tails will -never respawn-, and Sonic will have to either go backwards or hit the sandfall, the latter of which is an awful result because of a glitch coming up.
[1:14] Complete and utter fail for about 15 seconds here, couldn't make a catch to save our lives, and what's more Sonic lost the lightning shield. This doesn't make the next trick impossible, but it makes it much harder, and Tails has to play his part.
[1:41] Basically, Sonic and Tails both have to be pushed into the wall by the door, followed by Tails catching Sonic completely blind. The zip that immediately follows is why hitting the sandfall is awful: hitting either of them will cause this zip to stop working, and Sonic will die instead. Why? We have no idea. Just don't hit the sandfalls. EVER.
[1:54] Normally Sonic will have a lightning shield here, so as Tails you want to be flying straight up so Sonic doesn't pick up the water shield accidentally.

Lava Reef 1 (1:53) [-0:18]
[0:34] If Sonic and Tails are both on one of these elevators, their speed stacks.
[0:50] This one's virtually the same as Launch Base 1: just carry Sonic over to where the blocks are and he'll fall through them. Amusingly, Sonic will stay in position like that until Tails hits the ground.
[0:56] Sonic can get up here by himself with a ramp jump, but the ramps on this stage are really hard to see so Tails normally flies up here as cover.
[1:25] You want to make sure that Tails follows Sonic through this last section at least this far so that Tails is immediately brought to the boss room. This makes the first phase of the boss significantly faster/easier.

Lava Reef 2 (1:35) [-0:40]
For this level and this level only, we switch controllers, so I'm Sonic here. The main reason for it is to do the tube skip at the end of the stage (I'm much more consistent at it, unlike every single other trick in the game).
[0:15] The upcoming section is really slow with Sonic alone, so stopping to let Tails land here saves time overall.
[1:23] Time for the boss skip! Second attempt on this part, which is pretty good. The method I use is to spindash from the second X in the floor and jump from the last one, but on top of that you also have to hold jump for a precise amount of frames (I don't know exactly what this number is, but it's slightly more than a tap). It's something you get a feel for over time.
[1:32] Now I have to do two consecutive spindashes to escape the tube. This also has quite a small window, and in that small window you have to do the awkward press down -> A -> release -> press down -> A -> release movement. I don't think you have any more than two tenths of a second to do all of that, either. Third try isn't too bad here (extra attempts aren't incredibly costly) but I was getting it first time every time a couple of months ago, so I was kind of upset how my consistency slipped over time.

Hidden Palace (0:39) [+0:10]
We missed the quick kill! :(
If this was done correctly, instead of Knuckles punching Tails at 0:23, I would have entered Knuckles's sprite while he was being knocked back. From there Knuckles goes into his usual pattern so we just had to beat him normally, which is a real shame as it's undoubtedly one of the cooler tricks in the run.

Sky Sanctuary (1:08) [0:00]
[0:24] Pretty much all Tails does in this level is help Sonic skip that first moving bar.

Death Egg 1 (1:37) [-0:10]
[0:34] By keeping up all the way through this chamber, I was able to make this flight earlier and save a couple of seconds otherwise spent waiting for Tails to reappear.
[1:13] The boss basically goes like this: Usual Sonic strategy until Sonic gets hit, at which point the two characters just tank hits and get hits in while invincible. Second phase is very similar, but you need a good deal of luck. It's also worth noting (particularly as Tails) that the laser's hitbox extends a LOT higher than you think it should (see my attempt at hit 5).

Death Egg 2 (1:50 +33) [-0:55]
[0:02] Much like in Hydrocity 2, the death here is entirely intentional.
[0:15] Another similar one to Launch Base 1, Sonic looks up, and by lifting him upwards here Sonic is pushed into the wall. The trick coming up for Sonic here requires a frame-perfect lightning jump to get the best result; and if your luck is not in you don't even get a chance at said jump. That's what happened on the first attempt, costing us 29 seconds and the sub-30. :(
Thankfully, the second attempt was perfect and enabled the level wrap straight to the boss room. It has to be at a very specific height: too far up and you'll just be stuck in the wall, too far down and you'll appear on the right hand side of the tube, and be unable to get any hits. Even Tails can't get any hits because he will respawn at Sonic's horizontal position...
[1:20] At the beginning of this fight I always call out "2 and 5" - because Sonic and Tails stand on the 2nd and 5th tiles from the left of screen. This will line them up between two of the three fingers on each side and allow 10 hits total. Then it's just a matter of picking off the rest so that it only takes three rounds. Theoretically two rounds is possible but we've never managed to do it.
[1:46] Sonic and Tails combined can finish the laser boss in a single round. Basically Sonic gets two hits, then Tails two, then Sonic, then Tails. Whoever gets the first hit hits the nose from the left and reverses back into the laser like this, then just as the second hit is being delivered the person on the ground jumps. After that, both characters just hold left and jump as soon as they land back on the ground.
[1:50] The Trihex!! The least relevant strat for time, but the most relevant for style points. Would've liked to end the run with a one round kill, but not to be.

TOTAL TIME: 30:05 [-6:59]

I know sub-30 looks so close, and so appealing, from there, but it's rather simplistic to say we should have gone for six more seconds' improvement. For starters, this run is fucking -hard-. We probably completed 15-20 out of 600 attempts, and a good deal of them were ruined well before the end of the game. Secondly, the Death Egg 2 level wrap, which is one of the biggest time savers in the game, is both frame-perfect and luck-dependent, and it's the very last stage. There's also another one in Launch Base 2 which would save around a minute, but you can only attempt that once (unless you die, which just looks ugly).

Of course the biggest factor in not being able to improve the run is that now Mark and I not only don't live under the same roof, we don't live in the same state any more. Time together to grind and practice is pivotal to this run, and we simply don't have that any more. So the answer to "will this run ever be improved?" is likely to be "only if two other people do it".

Enjoy the run!

werster's Comments:

Hey guys, werster here, the guy that does all the skillful things in this run!!

(and all the dumb things)

This time honestly isn't quite as good as my expectations, however, this run has a lot to it. However, there are a bunch of ridiculous tricks in this run that make beating this time very difficult.

As with all co-op runs, both people have to be in the same space of mind (and earth) as well, so this time will take a lot of things to go right to be beaten.

Few terms to make understanding this run a bit possible:

Zip: In this game, a zip involves placing yourself inside a solid wall, and pressing a direction to move at high speeds in the opposite direction.

Level wrap: Underflowing your horizontal co-ordinate on the left most part of the stage to be placed at the rightmost part of the stage. This is used several times in the run, usually via a zip, as when vertically aligned with the boss room, the game is tricked into thinking that is where you are, and loads you straight to the boss.

Screen wrap: In certain levels, the stage is too large vertically, and in some cases, is forced to "wrap" upon itself vertically. In these stages, by scrolling the camera down and jumping, you can cause a "screen wrap" where the game tries to find the character. In this instance, you can pass through sprites and objects as they are not triggered when off screen.

Slope glitch: The instance of "no gravity" where you will stay on the same slope no with no tranistion to any other slope. This is usually triggered by standing on an object, and then having it broken by something other than you. This can be cancelled by touching another sprite.

Wheel Glitch: Exclusive to Carnvial Night, this glitch involves walking off ring boxes just below a wheel, which allows you to have the properties of the wheel in other parts of the level. That is; gravity is enhanced greatly and can be applied in any direction. This mode is cancelled by jumping under basic conditions; that is it will not be broken jumping off objects and out of Tails' hands.

Frame: In this game, it means 1/60th of a second

Sub-pixel: You should know what a pixel is. A sub-pixel is something smaller that...yeah. Dumbass rubbish gay shit that is generally not even in your control.

And into the run...

Angel Island 1: And the glitches start before the timer does. Doesn't take long to see how useful 2 players is. 48 is very standard here

~By breaking the water shield while the game is changing audio tracks, the track for Angel Island 2 never plays~

Angel Island 2: Another classical level, rounding off a solid start.

Hydrocity 1: Top route looks real nice with Sonic, but dumbass bullshit boss dick here, went very well considering.

Hydrocity 2: And now we start breaking shit. First level wrap of the game here, dying is intentional as underflowing is not possible in this level without first unloading Hydrocity 1 behind this level. Perfect run.

Marble Garden 1: And this is one of the levels you can Screen Wrap in. Really annoying level to co-ordinate between both characters. Payed for it on the boss, rest of level was pretty good.

Marble Garden 2: Fuck the fly at the start of the level dude, getting it first go is an instant win in my opinion. That gets missed like 90% of the time and that costs a whole lot more time than Mike derping at the start. Another level wrap here makes this level nice and short.

Carnival Night 1: Favourite glitch in the game here, and that's saying something. Wheel glitch can be really inconsistent, but this is nice. Gravity is reversed, and applied back to the start of the stage to force a level wrap.

Carnival Night 2: And then the application through this level, just awesome. Love the way this level goes with wheel glitch <3

Ice Cap: And now for some Slope Glitch action! In this case, it's done by Tails breaking ice that Sonic is standing on. I like how when Mike messes up and I have to wait for him to activate Slope Glitch he says "hang on" like I have anywhere to go. Sweet shit other than that.

Launch Base 1: In the case, by locking the screen upwards, and then having Tails carry sonic, sprites stay off screen. And once again, that means they won't trigger. You know how it goes from there by now. Very standard, hard to fuck up here

Launch Base 2: Dumbass bullshit glitch here that saves a full minute that I don't get...one of the main reasons I'm not completely happy with this run. It needs a perfect spindash (rev before release) and then a frame perfect jump to activate, so it's pretty hard. The back-up "actually playing the game" strat went alright though

Mushroom Hill 1: Most bullshit shit in all of shit. Sub-pixel bullshit going on here with no control at all complete random 50/50 chance between getting a level wrap and getting fucked and stuck in Knux's path...and that's once you get into the floor, which is so hard it's the only trick in the game I pause abuse! And it goes...awesome

~Getting that lightning shield is balls stupid cause it's right up against the wall...real annoying~

Mushroom Hill 2: Another rare glitchless level...goes pretty smooth, with a few minor errors

Flying Battery 1: Sonic dances...a bit too long for my taste. This glitch is weird, but Sonic is stuck in a "dance state" where he's confused between whether he is on a pulley, Tails' hands, or on the ground. By inserting Sonic into a wall and zipping out however, you get Slope Glitch of course! Wouldn't get his ass in the wall, couldn't tell you why.

Flying Battery 2: This is a really risky strat, mess this up and stuck forever, and that very nearly happened. Activate slope glitch in exactly the same way here, missed the roof clip a few times, but alright otherwise.

Sandopolis 1: Another level where co-ordination between the characters is very tricky...especially when your partner flies into spikes all the time. This goes pretty well though.

Sandopolis 2: This is another level where Screen Wrapping is possible. It's also probably the level that's mostly to go wrong, in that it'll never go perfectly. Bullshit fly dicks in the middle here, manage to clutch out some shit without the lightning shield, still wasted a huge bunch of time.

Lava Reef 1: This level sucks so much ass, uneven floors are stupid as hell.

Lava Reef 2: Switch! This is the one level where I play Tails, and it's all because of that wall skip at the end which I can not do on console.

Hidden Palace: Probably the worst level of the run hahahaha, this boss fight was absolutely dreadful.

Sky Sanctuary: Skip a huge bunch of the level, then fuck up the easy ass shit at the end.

Death Egg 1: Really intense level, Mike killed an even better run in this level by forgetting how to fly after going Tails' path. Level went really well here though...boss is always dicks but this time is pretty good.

Death Egg 2: And of course the last level in the game has a sub-pixel frame perfect jump that saves a full minute. First death is intentional to unload Death Egg 1, first time I get bodied by sub-pixels, got a second chance, and then my sub-pixels were wrong again, so I got an instant death that I had no control over. The second time, I got the frame-perfect trick and the level wrap to finish off the run.

Final Boss goes alright too.

Thanks for watching this really cool game!!