Important - due to a bug, if you retry a boss room on the same frame as the timer ticks up a second, your total time will increase by one second. Avoid this by pausing and retrying boss rooms roughly in between the passing of seconds. This cannot help you achieve a better time, and only applies to boss rooms.

So, this is kind of awkward - I've run my own game. I made Iji in 2004-2008, and upgraded it through 2008-2009. This is version 1.5, and this run is a 1:36 improvement on the one I uploaded to YouTube in 2008. It has mistakes, but they usually don't add up to more than a second per segment. Thanks to the SDA site crew (in case I forget to mention one of you), ExplodingCabbage for feedback and ideas, TheVoid for technical help, LLCoolDave for the Proxima improvement, the verifiers for verifying, and all the Iji fans for feeling that this game was worth it. Please post any questions about the run on the Speed Demos Archive forums.

Segments info:
Segment 1: Sector 1 (1:22, 1:22 total)
Segment 2: Sector 2 (2:21, 3:43 total)
Segment 3: Sector 3 (1:52, 5:35 total)
Segment 4: Krotera (0:08, 5:43 total)
Segment 5: Sector 4 (2:10, 7:53 total)
Segment 6: Sector 5 (2:45, 10:38 total)
Segment 7: Asha (0:03, 10:41 total)
Segment 8: Sector 6 (1:54, 1:35 total)
Segment 9: Sector 7 (2:59, 15:34 total)
Segment 10: Proxima (0:31, 16:05 total)
Segment 11: Sector 8 (2:05, 18:10 total)
Segment 12: Sector 9 (2:59, 21:09 total)
Segment 13: Iosa (1:06, 22:15 total)
Segment 14: Iosa2 (0:08, 22:23 total)
Segment 15: Sector X (2:30, 24:53 total)
Segment 16: Tor (2:25, 27:18 total)

In Sector format:
Sector 1: 1:22
Sector 2: 2:21
Sector 3: 2:00
Sector 4: 2:10
Sector 5: 2:48
Sector 6: 1:54
Sector 7: 3:30
Sector 8: 2:05
Sector 9: 4:13
Sector X: 4:55

SEGMENT 1: Sector 1
Note: The timer stops while Iji is in a chat dialogue, such as the ones at the start of Sectors. I need all the extra Nano I'm getting, or my level won't be enough for the stats I want later on. Time to start explaining the tricks I use: At 0:04 (referring to the current in-game time) I crush the crate beneath me by holding down in midair, even when I'm holding up at the same time. At 0:06 I jump out of the end of the wallclimbing animation to save a few frames. Similarly at 0:23 I jump out of the "use" animation. I don't want to jump too often though, as every time Iji lands on the ground she stops for one frame. 30 unnecessary jumps costs you a full second in this game. At the end of the Sector, the time is rounded down to the nearest second, and the remainder is tossed to that headcrab clinging to the back of your monitor.

SEGMENT 2: Sector 2
This part is hairy. The enemy AI in Iji is very random, so it tends to mess up your run. At 0:24 I take a rocket to the legs, but I'm okay since riding an elevator makes you invincible. At 0:30 I'm holding up on the keyboard, which makes me ride the elevator as soon as I step on it. At 0:47 I jump out of the landing animation, saving some frames. Next, checkpoints in Iji are not really savepoints, they just revive you once. I abuse this several times throughout the run. Abusing this particular checkpoint was ExplodingCabbage's idea, saving a few seconds. At 0:13 I perform a very hard jump, which might need some explanation in case you can't seem to replicate it... Iji moves at 5 pixels per frame. If you climb a ledge, you will slightly shift her positioning - she will no longer walk on pixels 1, 6, 11 etc, but pixels 3, 8, 13 etc. This makes certain jumps easier or harder. At 1:27, that Commander tends to mess up the run. At the end of the Sector I skip the cutscene - I'll skip every cutscene and dialogue that's possible to skip since they're not important to a speedrun.

SEGMENT 3: Sector 3
This is just down to playing perfectly. Which I didn't. At 0:06 the truce with the local Tasen is established because I killed less than 10 of them before entering this Sector - being peaceful also means the Tasen don't consider me a threat, which places less enemies in Sector 3 and 4. The game is crammed full of modifiers depending on your play, but they're usually more subtle than this. Anyway, at 0:33 you see a nice bug that lets me collect pickups just by landing on a platform immediately above them. At 0:39 I didn't need that Health level, I got it out of habit before the route in Sector 4 changed, but it didn't waste enough time to knock me down a whole second so it didn't matter. At 1:19 I meet the Komato scout team, who are not affected by the Tasen truce. At 1:40 I shoot at the Tasen (a rather special Tasen actually) to break the truce, which changes the upcoming boss battle and avoids the 10 minute penalty from Vateilika roasting Krotera.

SEGMENT 4: Krotera is a jerk
I can restart boss rooms as much as I like, treating them as their own segments. This is the fastest way I've found to steal Krotera's 25 HP away, hence the stats I pumped up until now - 25 Buster gun shots with an Attack of 4 does the job. I tried making Krotera finish himself by firing an MPFB shot into me, damaging himself, but it was slower than this strategy. Also, if he uses his supermove he becomes invincible even to his own projectiles.

SEGMENT 5: Sector 4
Shredders! Half of the Sector is built around them, you can even ride one all the way down to the end but it's slower. At 0:10 I perform a Nanofeld reboot (discovered in a logbook), resetting my stats and giving my points back at the cost of destroying any ammo above 10, and no longer getting free HP from Health stations until the end of the Sector. I should have done this Reboot at the start of the segment. I get another unnecessary Health level here, but luckily it didn't matter this time either. At 1:23, you can't climb Shredders while they're moving. At 1:56, I perform my last Reboot until the very end of the game, so from here on every stat investment will count. I reach the goal one frame before 2:11, meaning that a whole second of mistakes in this segment didn't count. :)

SEGMENT 6: Sector 5
This seems to be most peoples' favourite level due to the crazy battles going on. The Tasen and Komato prioritize killing each other, so Iji can usually slip by unnoticed, but did I mention how enemy randomness is frustrating for a speedrunner? Doubly so for this Sector. At 0:25 I wait with removing the message about my special trait, because I'm invincible while reading it, and I'm waiting for the Elite to take out the Troopers below. The damaged Elite goes to fetch the nearby health pickups which lets me through. At around 0:55, the Berserker dropping from the ventilation is random as long as you're in the right place, and I was lucky I got through before it triggered here. At 1:24 I was barely missed by the Commander giving the Trooper what for. At 1:44 there's a possible improvement; cracking a Resonance reflector while waiting for the Spread rockets to charge, as suggested by ExplodingCabbage. At 1:53 I perform one of the several sequence breaks I intentionally put in the game, skipping the dual terminals and the bottom quarter of the Sector. I grab enough Nano to get Crack level 9 and the Nuke. I finish two frames before 2:46. :p

SEGMENT 7: Asha lost even harder than Krotera
If you like surprises and don't know what I'm about to do in this segment, the following paragraph will spoil it! First off, you see my weapon changing from the MPFB in the previous segment to the Nuke in this - it's because I selected the Nuke, then restarted the boss room which remembers what weapon you have selected. The Supercharge is a reward for shooting Asha with this weapon for instant victory. Supercharges are generally hard to come by, and there's only one per Sector.

SEGMENT 8: Sector 6
I might as well say that enemy randomness is responsible for nearly every failed attempt in each Sector from now on. At the start, a single shotgun shot is not enough to destroy a barrel, and there's not enough time to switch to the Resonance detonator. At 0:21 is the run's first full-length MPFB Devastator jump - considerably faster and longer than a regular Rocket or Shocksplinter jump, so it's worth it. At 0:27 I leave the Assassin's range of attack, so she stops pursuit. At 0:46 I perform a Tech by pressing C at most a few frames before getting hurt, which nullifies regular damage staggering and greatly reduces knockback from heavy attacks, plus Iji lands on her feet. It's very useful, especially for speedrunning, eventhough you still take normal damage when doing it. At 0:54 I use a quirk in my rocket hitting the Turret, since it snaps to the left of the turret's hitbox and blows me to the right, rather than throwing me left into the pit below. At 1:49 I use the Resonance detonator on the door, and wait for it to recharge during Iji's dialogue. At the end you see me saving over a better time - when I got that one, FRAPS started lagging towards the end which ruined the movie. Figures.

SEGMENT 9: Sector 7
Enemy randomness again, and this is one huge Sector. It has several obvious mistakes. At 0:17 I take the upper path because those Komato tend to be annoying otherwise, but it's not the fastest option. At 0:20 I move the view with Numpad, comes in handy here. I jump into the Beast and Tech it, shooting it with a rocket and grabbing its Nano, but for some reason I go back left to take the upper path again, losing time. I grab the Armor upgrade because the rest of the run will be harder without it, especially facing enemies with Hyper pulse. At 1:19 I could have just jumped over the Turret, as long as it fired to the right (it would have turned and shot me in the back if I landed behind it). At 1:59 I don't jump out of that use animation, because I would just bump into the edge above. At 2:20, I can't MPFB jump in here due to the shape of the ceiling. At 2:50 I face to the right and Nuke myself over the hole, and get a guest appearance from a low-flying jet-Tasen.

SEGMENT 10: Proxima becomes confetti, costing 20 robot maintenance staff their jobs
I may have the advantage of having programmed its AI, but seriously, half the time I don't know what this thing is trying to do. You can make it confused by throwing it around the room with heavy weapons as it tries to get its bearings, but that's not useful here. After electrocuting Proxima, it will take a while for the terminals to activate - and let you recharge the electropads - but it's not based on time, but rather how many "orders" Proxima is executing. I found that Proxima can be trapped in a corner with a lucky MPFB shot after electrocuting it, which makes it skip orders and activate the terminals faster. At least that's what I think happened, I wasn't prepared for the terminal booting up so soon at first. LLCoolDave also mentioned that you can Nuke Proxima into the right electropad immediately as the fight begins. This seems to be due to a helpful bug that knocks it downwards rather than upwards even if it's a little bit above your vertical level. Iji's finishing statement here depends on how much of your maximum health is left at the end of the battle.

SEGMENT 11: Sector 8
Oh boy, more powerful enemies in tight spaces! This took about 50 attempts, most of them only a few seconds long. At 0:26 this Annihilator might grab me. At 0:30 this Elite might be blocking the MPFB ammo, and kicking Iji out of jealousy because her sprite has more interesting colors. 0:42 is perhaps the luckiest thing in the run - the Plasma bolt throws me to the ledge above at great speed. At 1:04, the next wave of ambushing enemies will spawn faster if you deal with the previous ones quickly. I have exactly enough ammo for four Nukes. Getting hit by the explosion at 1:13 and Teching it to avoid the ground-hitting animation was planned, I got this to happen about half the time I tried it. The dodging at 1:25-1:29 costs time, but it's better than being hit. At 1:32 the Trooper and Berserker get completely vaporized, no Nanofields for me. :( At 1:46 I'm trying to shoot the Troopers for extra Nano, but it didn't work this time. Iji throws herself into the following in-game cutscene with great haste. No, his life was not worth the 15 seconds to prevent that from happening. This is a speedrun bro!

SEGMENT 12: Sector 9
In this and the following segments, I'm running in fullscreen which enables the fullscreen gamma effects. In other news, this Sector has Berserkers and tight spaces. :) At 1:12 this Komato Annihilator and his good friend the Tasen Elite tend to ruin good runs. 1:49-2:01 might be the crappiest part of the game to run due to the Berserkers. At 2:03 I jump over the overload because it sometimes gives me Nanolife, which ruins the trick ahead since it recovers your HP when it hits zero. At 2:18, I would have been hit had I not climbed the ledge - Shocksplinter explosions have a massive range. At 2:33 I jump to destroy the lamp because I will get stuck in it while MPFB jumping otherwise. Notice that I fly over the health pickups leaving me at 3 HP - 2:49 completes the trick, saving a surprising amount of time backtracking. (The reason this checkpoint exists is for Deep Sector, not because the player might be dumb enough to blow herself up at the end of the level.) At 2:33 I take the opportunity to reposition my left hand with the middle finger on 4, index finger on R and thumb on C, to more easily perform the crack of the Velocithor. I look pretty funny while doing these runs already.

SEGMENT 13: Iosa has the best weapons in the game, Iji has the strategy guide
Might makes light! While the MPFB Devastator deals more damage than the Spread rockets, the latter don't knock you to the ground which makes for a faster fight. I really don't want to get grabbed out of the air. 3:12 is Iji's time to shine; Retribution requires the 8 basic weapons, 1 ammo for each and 5 or less HP on activation. You don't need to have read the log on how to do it; like Teching and Nanofield rebooting it's possible from the start of the game. Iosa takes a heaping helping of overly dramatic damage but is not impressed. At 4:01 I notice Iosa is about to fire an MPFB, so I jump into it in order to deal more damage to her.

SEGMENT 14: Iosa2 didn't get to show her moves
A timing quirk is found in this battle. When beating Iosa's first form, the time you took to beat her depends on the exact frame her HP drops to zero. The special effects and white screen flash afterwards do not count, which is why you briefly saw the timer go from 4:05 to 4:06 during the explosion in the previous segment, and back to 4:05 in this segment when I retry to fight her second form. So, no time has technically disappeared. Since this segment is so short I should have tried to mash through the cracking instead of being patient, there's a possible but extremely low chance that you get a clear path right to the end. Aside from that, Iosa2 is invulnerable to all Nanoweapons due to her personal nanofield. Boots to the head are super effective however. Can someone explain how that works? Her nanofield cracked and psyche BSOD'd, a Shotgun is all it takes after all.

SEGMENT 15: Sector X
More enemies and - no, this segment is actually one of the easiest, but as pointed out it's also the worst of the run. At 0:39 I Thor the core, skipping my favorite boss fight in the game, fought in a room shaped after Ridley's in Super Metroid. You can do this slightly faster by falling off the ledge while firing, which makes Iji fall to the ground during the dialogue. Also a nearby logbook states that the core is immune to the Nuke. At 0:57 Iji remembers that she's carrying the Velocithor and blows stuff up. After 1:28 it's all very easy, there's no chance of me getting hit, although taking the left path is faster. If you're very lucky you can jump past the Plasma Turrets at 1:42 without having to duck, but it's random how quickly it will spot you. At 1:45 I clumsily miss the teleporter, but unless I had touched it frame-perfectly it wouldn't have mattered anyway (compare the frames lost to how close I was to getting a time of 2:29). I Reboot and get Tasen 10 for the MPFB Devastator, Attack 10 for double damage output, 20% faster reloading and great justice, Assimilate 3 to have enough ammo, and Health 6 because I'll be taking a lot of damage, but it turned out to be less than I thought. Another time saver there. There's a Resonance reflector that you can't avoid picking up; it's there if you don't already have one when you get this far, and won't disappear if you do a reboot.

SEGMENT 16: Tor is beaten by simple math
This is a very hard segment due to the randomness of Tor's attacks. If he fires Fractal rockets, his next attack is delayed - this is the crucial part. He also increases the chance of firing any weapon he actually hits you with, even if you Tech them, and his weapons increase in power over time the more he uses them. What a lovely fellow.
Here are some stats:
Tor's HP: 900
Reflected chargeball: 83 damage
Full MPFB hit: 18 damage
Rocket hit: 4 damage
Every "round" of the battle, I get five MPFBs, one chargeball and one rocket in, for 177 damage total. In one of the rounds, I must get a sixth MPFB hit in order to remove the remaining 15 HP. I accomplish this during the round where he fires Fractal rockets. I don't want him to fire them too often though, or it pointlessly delays the battle. As for the Phantom Hammer, Tor only fires it if his HP is above 83-75% depending on the difficulty level, and he gathers three chargeballs at once. The only reliable way I know of to beat Tor faster is to let reallyjoel's dad play the game - I can't imagine how, but he'd probably win in ten seconds.