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A remake for the original 1994 game, UFO: Enemy Unknown, the game is set in the near future when a global alien invasion begins. A group of countries banded together to create XCOM (Extraterrestria Combat Unit), tasked with defense of humanity from aliens. As it turns out the invading race couldn't improve their own race further, and started searching the universe for species that could. As humanity's fate is on the line, could XCOM develop fast enough to take the fight to the Overseer UFO?

XCOMEnemyUnknown   XCOMEnemyUnknown

Best Time: 0:29:19 by Kevin 'Papers', 'Twyn' on 2014-12-28 done in 64 segments appended to unknown files.

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Author's comments:

Hello and welcome to the segmented speedrun of XCOM: Enemy Unknown. This run was done by Papers and Twyn on the 2012 release of XCOM without the EW expansion or any Second Wave modifiers.

XCOM is a strange and complicated speedgame with tons of variables and small optimizations. In these comments, I will attempt to explain the run so that as many people as possible will be able to understand what we are doing.


How the game works:

XCOM is a turn based strategy game with semi-random encounters. There is an ingame date and time which the player can accelerate to look for encounters. Several research trees allow players to upgrade their squad. Loot from enemies can be spent on research as well as items unlocked through research. Most researches also require a certain amount of in-game time to pass. The game also scales in difficulty with in-game time. To complete the game, the player must complete three story-essential missions, each unlocked through research of one kind or another. It is also possible to encounter a game over condition if you allow panic levels to rise too much around the world.

How missions work:

Missions are on randomly assigned maps pulled from a pool associated with a mission type (there are abduction maps, small UFO maps, medium UFO maps, terror maps, etc.). The exception to this is the last mission which is always on the same map. Units take shots with a percent chance to hit.

How chance to hit works (a tad technical):

Our understanding of chance to hit and damage rolls in XCOM has evolved dramatically over time, and there are still many things which we do not completely understand. I'll do my best to explain what we do understand, but you don't need to read this if in depth game mechanics don't interest you. XCOM seeds chance to hit at the time of map generation with the amount of time the application has been running. Using this single seed as well as input from the player, xcom continually generates new seeds to seed chance to hit. However, because only one rng seed is independant of the player and that seed is seeded at the start of the map, performing the exact same series of actions twice after making a save at the beginning of the map will, theoretically, produce the exact same results (This isn't exactly true because of the random nature of enemy movement). The difficulty is figuring out all the player inputs which seed a new seed. Attacks always seed a new seed, but other actions like explosives, spotting enemies, and critical strikes only sometimes seed a new seed. There are even fringe cases where the exact trajectory of a rocket or something which I cannot identify at all seeds a new seed. This makes routing each map and seed a fresh challenge, and can be extremely tricky on the larger missions.

Routing a speedrun:

Routing a speedrun of XCOM comes down to, in the fastest possible way, gathering the neccesary resources and research to unlock each story mission. Though we will upgrade our squad to some degree, we do not go out of our way in this run to gather resources for upgrades. The only resources spent on upgrades in this run are those incidentally gathered when gathering other resources or completing other missions neccesary to advance the game. During the run we will also dump the excess credits we earn into research labs to speed up research.

It is important to note that one of our main limiting resources in this run is weapon fragments, so we will be unable to use explosives against aliens in the early game.


Timing for each segment starts right after the load and ends the first frame that the saving globe appears in the bottom right of the screen. The globe fades in making it quite hard to see, but it is visible if you go frame by frame. The only exception is that timing for the last segment ends as soon as the boss's health bar dissappears, as this also marks the point at which the player loses control. Some segments in this run end with a manual save and some with an autosave. For the purposes of calculating SDA timing, I have noted below which are which.

QS - Ends with a Quicksave AS - Ends with an Autosave

Individual segment notes:

Segment 1 (00:00 QS)

This short segment rolls a ton of RNG. In addition to the map and hit tree, we also roll our base layout and timing for every mission for the rest of the first month.

Segment 2 (00:07 QS)

Moving all three soldiers who need to move before the enemy discovery cutscene starts is a few frame window and saves 2-3 seconds. How enemies move after discovery also has random elements.

Segment 3 (00:39 AS)

We finish up the intro mission and move on to a bit of menuing. We rank up all our soldiers (except our sniper who will not be used), start the story-relevant research project and begin excavating our base. This segment also has an important RNG roll. Upon ranking up, soldiers gain a random amount of the Will stat, 1-7 points. In this segment, we had to roll for all 7 points of Will on our Support in order to make her Psi Attacks down the line significantly more powerful.

Segment 4 (00:55 QS)

As you can see, the autosave while scanning loads to the zoomed out menu. This can be at times useful and at times irritating. What cities abductions will happen in is rolled in the first segment. This segment rolls mission rewards, number of enemies on each abduction, the map and the hit tree. We need to immediately start working on our engineer count and we want to go to Egypt because it is closer to fly to, so we roll for an engineering abduction in Egypt.

Segment 5 (01:09 QS)

Well this looks familiar. However there is a cool trick in this mission not in the previous mission. It turns out you can actually move your soldiers during the transition between discovery cutscenes, and if you do it late enough you can actually have the second alien pack calculate their movements without taking into account the new position of the soldier who is moving during the transition. This is the first of a number of tricks and exploits in XCOM which take advantage of the rough interface between a real time engine and a turn based game.

Segment 6 (01:39 AS)

We roll for an assault promotion since Run and Gun is overpowered early game. With our engineers from the mission reward, we then start building a Workshop and two discounted satellites.

Segment 7 (01:52 AS)

A short segment to make the next map rolling segment more bearable. We excavate another square of our base, start the Arc Thrower research and thats all. We will need an Arc Thrower later to capture live aliens and advance the story.

Segment 8 (01:57 QS)

Perfect UFO takedown and a good map. As far as I can tell, a 2 turn clear on this mission is actually impossible so I had to accept the 3 turn clear.

Segment 9 (02:17 AS)

This segment features an extremely rare and very random timesave which is hardly ever possible to set up. I position my squad in such a way that the second alien pack spots me while the first alien pack is still moving around. This causes the second alien pack to skip their discovery animation/cutscene and go straight to where they need to be.

Segment 10 (02:43 QS)

For the purposes of experience distribution, It is vital that our assault get 2 kills this mission and in every mission here on until Base Assault.

Segment 11 (03:21 AS)

We managed to loot 2 intact flight computers which is good. We will need 2 more and a UFO Power Source from the UFO next month. I ended this segment at one of the slightly earlier autosaves to break up some very difficult menuing and roll for more will on our Support.

Segment 12 (03:32 AS)

Short segment to take care of some exceptionally difficult menuing. I sell some corpses, alloys and the damaged power source to be able to afford to build a Satellite Uplink and excavate another square.

Segment 13 (03:42 QS)

As you may have noticed, we are completely out of cash. We'll use this abduction to take a credit reward since there are still a few facilities we need to build before the end of the month. At this point we will also start carefully controlling how many enemies we get on each mission so we have the exact number of weapon fragments neccesary to start the New Fighter Craft research after Base Assault. We have to have 6 here.

Segment 14 (03:55 QS)

Two turn clear on a 6 enemy mission is really hard, but we got it. Once again our assault and heavy each get 2 kills. This is critical.

Segment 15 (04:59 AS)

We skip the unimportant promotion and start a power generator and an access lift so we can move down to the second level of our base. We also need to sell a few more things in order to round out the spending for the month.

Segment 16 (05:15 AS)

We start Weapon Fragments research which will lead us to Experimental Warfare and allow us to have SHIVs for the first story mission. We then skip the council mission because they are really slow and build our Alien Containment which we need when we capture an alien next month. We then start excavating on the second level and start Experimental Warfare research as we continue towards SHIVs. We then launch our three satellites to North America right before the month ends. This awards us not only a lot of cash but 4 scientists and 4 engineers. We need to have 30 engineers eventually for later tech. The end of this month brings us to 18.

Segment 17 (05:35 AS)

In addition to the menuing, this is also the segment which rolls all encounters for the next month. We build an Arc Thrower so we can capture aliens, a lab to speed up research and a power generator to round out our power requirements for the rest of the game. We also excavate the last unexcavated parts of our base.

Segment 18 (05:45 QS)

Another map rolling segment with some deceptively tricky menuing as well. This took not as long as I feared it might.

Segment 19 (05:58 AS)

Alien successfully tazed! Also just a generally really nice fast mission. I'm pretty sure this is the least amount of turns you can do this mission in with the alien capture.

Segment 20 (06:58 QS)

This mission is 2 segments because of the blind click behind the building after the discovery cutscene.

Segment 21 (07:11 AS)

Hey look, panic. There is gonna be a lot more of that in this run. I use the early autosave again to make the last will roll on the Support. She will now have bonus damage to her Rift attack in the final mission.

Segment 22 (07:24 AS)

Another short segment with a low chance RNG roll. I buy scopes and then roll for the council request which will give me engineers for scopes. This is neccesary to meet the 30 engineer benchmark I mentioned earlier. Also fun fact: 2 rifle scopes can buy you the services of several professional engineers.

Segment 23 (07:27 QS)

I need a UFO with 2 intact power sources, 2 intact flight computers, 6 aliens, on a good map with a good hit tree set up in such a way that I can avoid or circumvent the annoying "hey look, alien tech" cutscenes and also set up so I can get 2 kills on my Assault and 2 on my Heavy. This would have been borderline impossible in one segment. Fortunately, the loot and number of aliens on a mission is not rolled when you start a mission but when you shoot down the UFO. For this reason, I divided shooting down the UFO and starting the mission into two segments. This also allows us to roll for a fast UFO takedown.

Segment 24 (07:46 QS)

A map roll segment. Nothing to see here.

Segment 25 (08:03 QS)

But what a map roll it was. A 2 turn clear with the outsider stun and being set up to take shots during the power source cutscene is absolutely amazing. My Assault and Heavy also got their neccesary kills. This is one of my favorite parts of the run.

Segment 26 (09:04 AS)

I actually manage to scan, finish experimental warfare and start the sectoid interrogation all before the autosave on a timer from when I go to mission control happened. Pretty nice. I have to slow down a bit in the soldier promotion to give my assault the Rapid Fire ability as this will be important later. The sectoid interrogation will unlock the Outsider Shard research which will in turn unlock Base Assault, the first story mission. We have now completed the last optional mission of the run.

Segment 27 (09:24 AS)

Though we finish the interrogation in this segment, we do not go straight for Outsider Shard research and Base Assault. Instead, we research some of the prerequisites for the New Fighter Craft research we will need for the next story mission and start a Foundry so we can get SHIVs. SHIVs are robotic units which have strong stats and good mobility. They will be featured heavily throughout the rest of the run. We also quickly pick up some scopes to fulfill a Council Request later.

Segment 28 (09:43 AS)

A really tough segment because of the random nature of a lot of the popups we have to skip through. The UFO we skip at the start causes another UFO to come at a random timing which we also want to ignore. When the terror mission comes is also random. All this not to mention getting the correct Council Request to help us meet our engineer quota is like a 1 in 8.

Segment 29 (09:59 AS)

After getting through the prerequisites for New Fighter Craft, its finally time to research Outsider Shard and go do Base Assault. The SHIVs finish just before the end of the month and now its time for a cool little trick. Our panic levels mean that we will lose countries if the month ends. However, to fill our weapon fragment quota, we need to do Base Assault in May, not April. So we manipulate the autosave to happen as late in April as we can. This way by the time the Skyranger arrives at the mission site it will be May, and when we get back we will have the global panic reduction from Base Assault and will not lose a country.

Segment 30 (10:09 QS)

Map roll for Base Assault.

Segment 31 (10:29 AS)

Shooting things. Sadly we can do nothing about this cutscene.

Segment 32 (11:41 AS)

Camera does some very strange things on Base Assault when loading a save. That jump at the beginning is the least extreme of the possible things which can happen.

Segment 33 (12:33 QS)

As you can see, sometimes loading a save at Base Assault will just not put your camera in the right place. This is irritating but we can't always avoid it. Also a cool setup to get shots off during the cutscene.

Segment 34 (13:12 QS)

A strange segment only neccesary because of a weird bug where we kept triggering floaters on the other side of the map. This almost always happened when we ended our turn here except for rarely they would randomly not trigger. This triggering ended up losing a lot of time so we made this intermediate segment to prevent that from happening. How the floaters which we intend to trigger move after they have been triggered is also random and we had to roll for a very particular formation. In all getting good RNG on this segment was about a 1 in 50. Certainly not one of the hardest segments in the run but one of the most irritating.

Segment 35 (13:34 AS)

We see chryssalids for the first time in the run. These guys sadly can't be one shot with any weapons we have right now.

Segment 36 (14:34 AS)

Sometimes its possible to make the camera to focus in on one of our units by spamming tab as we load into the segment. We use this here to get the camera to center in on the right SHIV from the start. This segment also makes the first use of our assault's newly aquired rapid shot ability to take two shots in one turn. We end the segment here to roll some very difficult enemy positioning rng in the next segment.

Segment 37 (15:08 AS)

The annoying camera position at the start of this segment doesn't lose time because we use the time to switch our assault's weapon back. We will only be bringing 3 units into the final room since that is all that is neccesary to clear it effectively. This segment just brings our 3 squad members to the entrance of the last room and reloads their weapons, however it also rolls a lot of rng regarding enemy positions for the next segment.

Segment 38 (15:58 AS)

Having our units spread so far across the map can cause several problems which we have to find a way to avoid. First of all, loading a save puts the camera into an even less reasonable position so we spam tab at the start of the segment to get it to center on a unit. The second problem we will encounter is that upon ending our turn, the camera is going to want to run all the way back to a unit in the previous room we had selected at the time. Fortunately, Vahlen's dialogue upon using the explosive stops that from happening (We are able to use explosives here because chryssalids have no weapon fragments we need to recover). At the end of the segment, you see what I mean by the camera wants to run back to the units in the other room when ending the turn. Here we let that happen and then segment right after so that we can use the tab spam trick in the next segment to avoid having to scroll all the way back to the final room.

Segment 39 (17:01 AS)

We tab spam to our assault here, activate run and gun, trigger the sectoid commander and the cutscene and then run in for the kill. Triggering the cutscene with our Assault would have disabled him until the end of the cutscene so moving the SHIV is a neccesary step.

Segment 40 (17:34 AS)

We now have the exact number of weapon fragments we need along with all the prerequisites to start New Fighter Craft research, so we do so immediately. We begin our third and final lab and grab our squad size upgrade as well before selling off a few things we got from the Base Assault to fund us from now until Overseer. Once the New Fighter Craft research completes, we start Hyperwave Communication research which is a prerequisite for finding the Overseer UFO and build a Firestorm and 4 Hoover SHIVS which are just better versions of the previous SHIVs we had. The Firestorm is the entire reason we needed New Fighter Craft research as it provides the speed and armor penetration neccesary to take down the Overseer UFO once we can detect it.

Segment 41 (17:59 QS)

We lose a second satellite to UFO attacks in this segment, something which will actually be important later. We finish the Hyperwave Communication as well which lets us build the Hyperwave Relay, the actual thing which will allow us to detect and go after the Overseer UFO. We also start EMP Cannon because even a Firestorm can't take down the Overseer with just torpedoes. We end the segment right after EMP Cannon research completes and after starting the Sectoid Commander Autopsy we will need for the next story mission, but before the end of the month so that we can roll the seed for the next month in the next segment.

Segment 42 (18:23 QS)

A short segment to roll the timing of missions in the upcoming month, the most important timing being the timing of the arrival of the Overseer UFO. We build and equip the Firestorm with the EMP cannon using the money and engineers we gained at the ouncil report (This is one of the items which requires 30 engineers), start scanning to start the autosave timer, and then get lucky enough that the Overseer UFO is discovered inside a 3 hour window after our Firestorm is finished being armed with the EMP Cannon and before the Sectoid Commander Autopsy completes.

Segment 43 (18:30 QS)

Getting a good seed for Overseer proved not as hard as feared partly due to good luck and partly due to our growing understanding of the workings of rng in XCOM at this late stage of the run. Our squad works well together too. Our Assault murders things with his crazy crit bonuses, our Heavy rockets things and our hoover SHIVs have amazing movement and can set up scenarios which would be impossible with soldiers or even regular SHIVs.

Segment 44 (19:02 AS)

It doesn't look it, but this was probably the hardest execution segment in the run due to the odd interaction between unit movement and selection ordering. The rocket positioning not only has to hit in a tiny window to hit all three targets, but has to hit in the lower half of that window or else chance to hit gets screwed up (don't even ask, I have no idea how this could possibly affect chance to hit, but it does). This in addition to many other annoyances meant this segment took almost a month and over 20 hours of attempts.

Segment 45 (20:19 AS)

Managing to take shots over the flight computer cutscene is pretty neat. This took a lot of routing to set up. The second turn is actually extremely technical. I don't understand everything which makes this route work, but I'll do my best to explain what I do understand. The devs of this game have described enemy movement as being on patrol paths. However, a better description of enemy movement is that they teleport from waypoint to waypoint and draw event triggers between waypoints they move between to check if they should play the discovery animation. What I have done in the second turn is to move one SHIV to block the waypoint they originally intended to teleport to, while making a clearing around their backup waypoint to encourage them to teleport right on top of me.

Segment 46 (21:21 AS)

Being able to rocket things is nice. The SHIV which we sent up to block the waypoint is now going to loop back and play an important role in the final room fight.

Segment 47 (22:03 AS)

Horrid rng segment. The mutons never like to move towards me, but they do like 1 in 10 times. Of note: this segment marks a few different firsts in the run. In this segment we take the first damage which we have taken all run, and the aliens take the first combat turn which they have taken all run. It would have been cool to go through the entire run without a single enemy turn taken, but if the enemy wants to spend his turn dealing 14 damage to himself, I have no objections.

Segment 48 (22:50 AS)

Rifts tick twice, the second tick does more damage. We save the SHIV because it costs more time to sell the items neccesary to purchase a new one than to just move it back a unit. Sadly, the other SHIV we can't really save. Rest in Peace Lightning 2, he gave his life so that we might go fast.

Segment 49 (23:12 AS)

There are some big purchases we have to make to unlock the final mission so we take some time to sell stuff. A cool trick for selling large stacks of items is that you can spam click the arrow and tap the arrow key simultaneously and both input sources will register. We will need two building slots also to finish out the run. Alien Containment is no longer being used and can be removed. We have also managed to lose enough satellites to UFO attacks at this point that we can remove the Satellite Uplink we built to give us a boost early in the run. We use one of these slots now for the Psy Labs which will allow us to obtain psy soldiers, a neccesary part of unlocking the final mission. We also start the Ethereal Device research which will allow us to build the Gollop Chamber.

Segment 50 (23:22 AS)

In this segment we build the Gollop Chamber which will be used to activate the final mission. We also pick up the Laser Shiv upgrade and a few prerequisites. This upgrade will allow us to one shot several enemies on the final mission and will save a lot of time. We end the segment by starting the Psi Armor research and placing our Support into Psy testing.

Segment 51 (23:45 QS)

The final stretch. We get back our Support from testing, now with psionic powers, equip her with the Psi Armor which we just bought and enter the Gollop Chamber. (Notice the exactly 0 credits we have after buying the Psi Armor :D)

Segment 52 (24:09 QS)

Temple Ship is the only mission which has the same enemies on the same map in the same places every time. Because of how our route works, we only need to bring 5 units.

Segment 53 (24:22 QS)

We hit a moderately precise rift to take care of the enemies in the lower room. The sectoid commander takes some pot shots at us, but its faster to let the second tick of the rift kill him than to actually shoot him. When he dies, 2 cyberdisks and 4 drones are gonna try to spawn. However, saving and loading at the correct timing permanently despawns them.

Segment 54 (24:53 QS)

A surprisingly difficult movement segment and a grenade throw. This segment is short because it ends with a camera warp. Though the Temple Ship map is as large as the Base Assault map, for whatever reason the camera here isn't broken. Selecting the unit we want to center the camera on and then saving and loading will actually center the camera there.

Segment 55 (25:18 AS)

A really tight triple move before the game takes over our camera and a nice crit.

Segment 56 (26:04 AS)

This triple move isn't just really tight, as far as I can tell it's actually impossible... unless you nudge your camera to the left before starting. It loses a bit of time, but I never got it once without nudging my camera.

Segment 57 (26:34 AS)

This rift is a good deal less precise than the last one. Rifting the thin men is especially important as then tend to clog up the door with poison if you don't. The segment ends with another camera warp.

Segment 58 (27:20 AS)

Easy segment to set up the next segment.

Segment 59 (27:53 AS)

A super precise rift positioning lets us pull off this neat trick. I'm not exactly sure why the beserker behaves like that, but it has to do with the fact that beserkers move each time they take damage. Somehow we've abused that movement code.

Segment 60 (28:36 QS)

The first segment where it has really hurt that camera rotation isn't preserved through saves. What we do here is place our psy soldier at a specific spot where she can see the sectopods without triggering them. For whatever reason, this gives us faster turn passes. We them spam end turn 4 times and we have rift back. Mechanical units take a ton of damage from rift since they technically have 0 will. The segment ends a bit late because we actually despawn two muton elites with the end of the segment. However we wait a bit because making the save too early results in a softlock by causing the door to the final room to not open.

Segment 61 (29:00 AS)

A camera warping segment as we approach the final room.

Segment 62 (29:10 AS)

Another camera warping segment. This segment proved to not be strictly neccesary for an odd reason.

Segment 63 (29:21 QS)

There is so much to talk about here I'm not even sure where to start. We want a rift for the boss so we have a turn to burn. We burn it outside the room to give the door time to open (saving and loading apparently causes the door to close and then open again after 5 seconds). However there is a problem. Walking up to the boss will cause a 1 minute cutscene to play. For this reason, we place our psi soldier just outside the sight range of the boss and move our SHIV up to the platform where a very special tile is located. This tile will allow us to trigger the boss without triggering the cutscene. No, I don't know why this tile exists and there is no equivalent tile on the other side of this otherwise symetrical room. Making the rng for the next segment work is also super strange. I don't know if it has to do with the skip we are using or what, but I cannot seem to identify what affects the chance to hit in this room. Getting a working save in the final room pretty much came down to pagan rituals and prayers.

Segment 64 (29:40)

Remember that our psi soldier is still out of range of the boss, so this rift is actually extremely precise.

And that's the game. The cutscene is a bit screwed up because SHIVs don't show up in cutscenes and because for some reason they just assumed that your chosen one would be male and voiced "him" over accordingly.

That's all, thanks for watching!

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