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X-COM: UFO Defense

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Title Screen

X-COM: UFO Defense

Also known as: UFO: Enemy Unknown (EU)
Developer: Mythos Games
Publisher: MicroProse
Platforms: DOS, Amiga, PlayStation, Windows
Released in US: May 1994
Released in EU: March 1994

AreasIcon.png This game has unused areas.
GraphicsIcon.png This game has unused graphics.
ItemsIcon.png This game has unused items.
Sgf2-unusedicon1.png This game has unused abilities.
MusicIcon.png This game has unused music.
SoundIcon.png This game has unused sounds.
TextIcon.png This game has unused text.
RegionIcon.png This game has regional differences.
Carts.png This game has revisional differences.

ProtoIcon.png This game has a prototype article
PrereleaseIcon.png This game has a prerelease article

X-COM: UFO Defense is a turn-based tactical combat game with elements of global strategy, resource management, RPG, and even a bit of arcade. Intercept and shoot down UFOs, capture aliens, protect cities from acts of terror, and study your enemies to fight them better. The game spawned two less successful sequels in the same genre, two more failed sequels in different genres, and more recently a very successful reboot in XCOM: Enemy Unknown.

A lot of info about the game's internals is collected in the fan wiki https://www.ufopaedia.org/index.php/X-COM

Sub Pages

Read about prototype versions of this game that have been released or dumped.
Prototype Info
Read about prerelease information and/or media for this game.
Prerelease Info

Version Differences

DOS Version 1.0

Released As: UFO: Enemy Unknown
Release date: March 1994

The first release of the game, released only in Europe under the games' original name of UFO: Enemy Unknown.

  • As with all DOS releases of the game, has broken difficulty settings where due to a bug, any game played after loading a save in the Geoscape will fall back to Beginner difficulty no matter what it was originally set to. Since the Geoscape and Battlescape are two different executables, this includes simply finishing a mission. This bug was only fixed in the Windows version of the game that came in the later Collectors Edition.
  • There is a corrupt map file UBASE_07.MAP which can prevent alien base attacks playing properly. See the 1.1 version below for more information.
  • Many other bugs as detailed in the patches for subsequent versions of the game.
  • The inventory/equip screen doesn't yet have the button to view extra pages of/sort items on the floor, making it difficult to pick up items when there are lots on one tile.
  • The Tactical executable still has most of the text from the PC Format demo about a UFO crashing in the Amazon jungle.
Equip Screen v1.0 Equip Screen v1.2
UFOEU-1.0equip.png UFOEU-1.2equip.png

DOS Version 1.1

Released For: UFO: Enemy Unknown
Release date: April 1994? (based on archive file stamps)

Apparently some copies of the game in the UK shipped with this patch on a fourth floppy disk[1][2].
This patch only contained map files.
While the archive contains replacements for all the game's map files, in fact the issue intended to be fixed here, both according to the included readme and research on the internet, is a corrupt alien base map file that caused the so called "Y-AXIS" issue. This was due to a corrupt map file UBASE_07.MAP, which if chosen for use in the game in an alien base attack would result in it showing the message "CAN'T FIX Y-AXIS" on a black screen, preventing further progress in the game. All future patches included this fix.

(Source: GOG discussion thread)

DOS Version 1.2

Released As/For: UFO: Enemy Unknown, X-COM UFO: Defense (First official USA release, in the last days of May 1994)
Release date: April 1994

The basis for what would become the first version of the game to be released in the USA later that year under the alternative X-COM UFO Defense name, with the new name shown in the intro and title screen. Note that the USA release still contained a large amount of British English.
Contains the map fix from version 1.1 and many other fixed bugs.

  • Removes the text from demo in the Tactical executable
  • Introduces the button to be able to view more pages of/sort large numbers of items on a single floor tile

Official changelog:

Please start a new game to eliminate all possibilities that the new version of the game fixes the bugs which you have seen so far.
The SETUP program does not require that you set the IRQ settings for the sound card, only the Memory address and the DMA channel. The normal Soundblaster defaults for this is, Address A220 and DMA 1. If you find the game crashes before you have a chance to play then this is likely the reason.

This update contains a new version of the DOS Extender, DOS4GW to fix some compatibility problems seen with the earlier release. DOS4GW is not a MicroProse program and we were not aware of these compatibility problems until after UFO was published. If you had a problem running UFO, this update will fix that.

Corrupt tiles that caused multiple images to appear have been fixed.

Action points (TU) have been limited to 80 to prevent the "wrap-around" problem seen with the original release.

Mission variety has been improved to allow access to all types of missions when playing.

Alien intelligence has been improved to allow a tougher game.

UFO encyclopedia has been expanded to include missing entries.

The corrupt game file, UBASE_07.MAP which caused problems when entering the Alien Bases has been replaced.

There is no PC Speaker support within UFO.

The Environment Space error has been fixed.

DOS Version 1.3

Released For: UFO: Enemy Unknown
Release date: September 1994

This was a follow up patch only for the original UFO: Enemy Unknown game, not the later X-COM: UFO Defense.
Changes were made for some item costs.
Official changelog (note this is cumulative so many of the fixes listed were already present in 1.1 and 1.2):

 * Please start a new game of UFO to eliminate all possibilities
that the new version of the game fixes the bugs which you have
seen so far. Your currently saved old games may not work properly
on the new version - sorry!

* The SETUP program does not require that you set the IRQ settings
for the sound card, only the Memory address and the DMA channel.
The normal Soundblaster defaults for this is, Address A220 and DMA 1.
If you find the game crashes before you have a chance to play then
this is likely the reason.

* This update contains a new version of the DOS Extender, DOS4GW to
fix some compatibility problems seen with the earlier release.
DOS4GW is not a MicroProse program and we were not aware of these
compatibility problems until after UFO was published. If you had a
problem running UFO, this update will fix that as we have managed to
obtain a later release of this program.

* Corrupt tiles that caused multiple images to appear have been fixed.

* Action points have been limited to 80 to prevent the "wrap-around"
problem seen with the original release when points reached over 250
and then went to zero.

* Mission variety has been improved to allow access to all types of
missions when playing.

* Alien intelligence has been improved to allow a tougher game.
Aliens are now more aggresive and carry more powerful weaponary in
their spaceships. They will also no longer stand around and wait for
you to come to them, so watch your backs!

* The UFO encyclopedia has been expanded to include missing entries.
If you research a new item and no information is displayed after the
research period is up then this is because nothing new has been learnt.
This is not a bug.

* The corrupt game file, UBASE_07.MAP which caused problems when
entering the Alien Bases has been replaced.
This previously caused the error, "CAN'T FIX Y-AXIS" to appear when
entering these bases.

* There is no PC Speaker support within UFO as specified in the
Technical Supplement.

* Some customers reported the MS-DOS error,
"Note enough Environment Space" when attepting to run the program, if
more than four SET commands had been made from the AUTOEXEC.BAT file.
This has now been fixed

* A few customers reported a problem where captured live aliens were
dying, on route back to base, because there was no Alien Containment
facility available for them. This despite the fact that the facility
was there and it was empty or only partially full. This problem was
not easily reproduced but has now been fixed in this version.
(Source: comp.sys.ibm.pc.games.strategic post by Tim Chown)

DOS Version 1.4

Released For: UFO: Enemy Unknown, X-COM: UFO Defense
Release date: March 1995[3]

The Final DOS version of the game. Unfortunately the official patch notes only include installation instructions for the various versions of the game (UFO/X-COM and CD/floppy disk) and do not list any of the fixes or changes made to the game, aside from Gravis UltraSound users now being able to hear all sounds in the game. It also advises keypad + and - can now be used to change music volume in-game.

  • Removes the manual password copy protection
  • Changes many sound effects to alternative versions. See below sound comparison section for details of what was changed

Early patch notes from Microprose as posted on Usenet in November 1994:

Hi All,

I know there are quite a number of people anticipating the XCOM update,
and here is the latest information from MicroProse UK:

This update, available shortly before Christmas, will upgrade the Sound &
Music in X-Com/UFO as follows;

1. Stereo FM music for OPL3 chips.
2. Full sound and music support for Gravis users.
3. Eight channel stereo digital sound for all
SoundBlaster Pros and compatibles.
4. Improved sample quality throughout game.
5. Full music support for Ultrasound, AWE32, Sound Canvas,
Soundman Wave, Soundscape and "General Midi"
6. Latest version of game.

However the game MAY now require 4Mb to run, depending on sound options


Windows Version/X-COM Collector's Edition

Released As: X-COM: UFO Defense Gold Edition
Release date: November 1999

A one-off Windows version of the game released on CD-ROM in 1999. This is based on DOS version 1.4 so has the later sound effects only.

  • Oddly no longer features any sound effects during the intro sequence, just like the Amiga CD32 version
  • The first (and only) PC version of the game to finally have the saved game difficulty bug fixed
  • Notoriously has a new bug where making a blaster bomb fly up to a tile directly above/below itself causes it to move at an angle instead, making it impossible (or at least extremely difficult) to send up elevator shafts in UFOs.

According to comments reportedly from Microprose's Dave Ellis on Usenet, the conversion team didn't try to fix any of the other bugs from the original game other than the difficulty bug[4], likely due to not wanting to accidentally cause more problems, and the fix being extensively documented by the fan-made utility XComUtil.

The main executable features the following hidden text:

XCOM: UFO Defense Gold Edition This awesome game was compiled on Sep  8 1999 at 08:57:11 Copyright © 1999 Hasbro Interactive/MicroProse Software Party on dude.

Amiga AGA Version

Released As: UFO: Enemy Unknown
Release date: 1994

Note: There is no evidence that any of the Amiga versions were released in the USA/released under the later X-COM: UFO Defense name
This was the first Amiga version, released in 1994 and compatible only with AGA Amigas (i.e. Amiga 1200 and 4000). Coming on 4 floppy disks it was mostly on par feature/gameplay wise with the PC original with identical 256 colour graphics. However, perversely it has things missing even compared to the other Amiga versions:

  • Lacks the PC intro with the soldiers taking off in the Skyranger on alert. There is simply a Microprose logo and the UFO: Enemy Unknown logo faded in.
  • Has a unique soundtrack that is both different not only from the original PC version but also the later Amiga OCS version.
  • It's completely unknown who composed the music for the AGA versions. The music is also in the esoteric .MUS format.
  • Compared to both the PC and OCS versions, it's also missing music in some screens. Most noticibly the Battlescape has no music, but there are also fewer tunes than the PC version in general. There is only one Geoscape song instead of two.
  • Uses the exact same sound effects as the original DOS release of the game, with a few effects missing and some samples slightly lower in sound quality. The Celatid attack sound is missing, and so are the snow footstep samples.
  • Some minor animations are missing. For example, the yellow pointer highlighting the currently selected soldier does not move in the Amiga versions. Smoke also does not animate.
  • Has a simplified text-only enemy turn screen without the graphic of the soldier being stalked by an alien. This was a deliberate compromise to improve the speed of alien turns[5]
  • The globe in the Geoscape view is not textured in any of the Amiga versions of the game, and neither is there any day and night shading.. Because there is no distinction between day and night in these versions.
  • The biggest and most disappointing difference from the PC version is there are no night missions. All missions regardless of time of day play as if they are in the daytime without the night shading effect of the PC version, and this also seems to effect gameplay elements such as visibility, which is always at day levels. The end result is the electroflares are useless items in the Amiga versions of the game.
  • The Amiga versions do not seem to be affected by the difficulty bug
  • Generally sluggish performance on an unupgraded Amiga 1200.
  • Features password copy protection where a code from the manual must be typed in before play.

Amiga CD32 Version

Released as: UFO Enemy Unknown
Release date: 1994

This was the second Amiga release of the game, also released in 1994, on CD. Intended as a somewhat further enhanced edition of the AGA version but for the CD32 games console. This version comes frustratingly close to being the definitive edition for the Amiga, but has some massive and quite bizarre issues due to the game console's notoriously tiny 1kb NVRAM used for saving games that effectively ruin it.

  • Includes the full PC intro with the soldiers scrambling. This is identical to the PC version, but has a MOD version of the music playing rather than the original MIDI music, and like the later Windows Collector's Edition also does not include any of the various sound effects, such as in the scene when the Mutons are gunning people down.
  • Aesthetically identical to the AGA version, 256 colour graphics
  • The same base soundtrack as the AGA release, but with more music now included. Bizarrely a file for the Battlescape music is present on the CD, but this is still not played at all in the actual game.
  • Supports both mouse and CD32 pad control
  • Limited to only building three bases in the game. This is due to the lack of saved game space on the console.
  • Bases and soldiers cannot be named/renamed (presumably due to the CD32 having no keyboard)
  • After saving a game and loading it to continue, all soldiers will default to the black female character model. By the end of the game you will have an army of ebony Amazons with names like "Geoff". This seems to be a deliberate compromise caused by lack of space to save this information - although given how the game generates soldier sex and ethnicity based on the namepool, and this version doesn't allow you to customise the names of your men, that compromise actually wasted save capacity.(!)
  • Another saved game limitation is that after saving and then reloading a game, all craft will have no items or soldiers equipped - they must always be reconfigured again after loading a saved game. At least the base's storage capacity is as broken here as in other official releases.
  • Only one game can be saved at a time on the console. The player must be committed to playing as well, as saving the game uses up ALL the console's NVRAM space, deleting any other game saves present and preventing the saving of any other files on that console (unless the UFO save is overwritten).
  • No password protection.

Amiga OCS/ECS Version

Released As: UFO Enemy Unknown
Release date: 1995

The final and worst of the Amiga versions. Released in 1995 and designed to run on the then obsolete and far underpowered Amiga OCS chipset (as found in the popular Amiga 500), the game runs with a massively reduced number of colours meaning all graphics are hugely inferior to the PC original, and also the Amiga AGA versions. Oddly, despite being objectively the worst version of the game ever released, it was programmed by a different team to the AGA versions and has some new features included that were missing from the other two Amiga releases. It also came on five floppy disks unlike the AGA version, with the extra disk used for the cut music and art outlined below. Game differences include:

  • No full intro the same as the AGA version, but this time the UFO splash screen logo simply appears and does not fade in.
  • Reduced colour palette compared to PC and AGA versions with only 32 colours on screen. Most of the background panel graphics are simply now in greyscale.
  • Features a totally different soundtrack to the AGA Amiga versions, this time based on the original PC music. This time there is actually music played in the battlescape. However there is only one tune for both starting a mission and attacking an enemy base, unlike both the AGA versions and the DOS original.
  • Music in this version composed by Matt "4Mat" Simmons. He has confirmed he only composed the OCS version music [6]. Music in this version is in the common Amiga Protracker format.
  • Vastly reduced number of sound effects. Soldiers and aliens now have no death sound.
  • Reduced sample rates of sound effects (most noticeable on the Geoscape clicking sound effect)
  • Features the enemy turn screen graphic from the PC version with the soldier being stalked by an alien that is missing from the AGA versions
  • A new feature not seen in any other version of the game where a progress bar shows during the enemy turn to indicate how far through calculating the enemy turn the game is. Likely added due to single turns infamously taking anything up to 45 minutes in this version of the game.
  • Uses a new, different mouse cursor graphic to the AGA versions.
  • As with the AGA versions, no night missions.
  • The game defaults to a low memory mode where units have no moving animations(!). Soldiers do not actually walk, they simply glide around the map when moved. This can be changed on machines with more memory to show animations again.
  • New weapon firing effect - rifles now fire laser-like beams instead of projectiles and the screen flashes when fired.
  • Very poor in-game performance on an Amiga 500.
  • No password protection.

Sandwiching the text for various error messages in the main tactical executable in the OCS version are the lines:


An inexplicable phrase perhaps familiar to readers of Viz magazine. This text is not present in the other Amiga versions.

Playstation Version

Released as: X-COM: Enemy Unknown, X-COM: UFO Defense
Release date: 1995

A port to the original Playstation games console with many enhancements.

  • Confusingly released as X-COM: Enemy Unknown (not UFO) in Europe only, predating the identically renamed reboot by a good 15 years.
  • New Title/Menu screen graphic
  • Has new FMV cut scenes on completion of a mission. Success results in a video showing dead aliens and the pilot of the Skyranger giving the OK sign while landing in front of a cheering crowd. Failure shows a leering Muton executing the pilot as he tries in vain to dust off, before a secret funeral with a series of coffins with helmets on is seen. Abandoning the mission shows the pilot leaving a fallen soldier to rot, but escaping alive. There's also a new ending cinematic, featuring some old fashioned CGI - remember that Toy Story took supercomputers almost an hour to render each frame - rather than the hand drawn comic book style used for the rest of the videos.
  • New soundtrack featuring CD audio by Allister Brimble based on original DOS music.
  • Sound effects are mostly the same as DOS v1.0 with some few new sounds. For example, tank movement sounds, bullets hitting walls, the door opening sound, and plasma impact sound effects are all new compared to any DOS version.
  • New background of a nebula/space behind all geoscape and also soldier inventory screens.
  • Features a new pop-up keyboard interface due to it running on a games console without a keyboard accessory (this was before USB was invented).
  • Different smoke effect graphics.
  • Redone Ufopedia. All pages have been graphically redesigned, and vehicles now have pre-rendered 3D animations that play showing them off.
  • Unlike other versions of the game, the final Mars base map is a pre-set map, and is not randomly generated.
  • The save takes up the whole megabit on a PS1 memory card. (128 times the capacity of the CD32 version!)

Unused UFO Components

UFOs and alien bases may have a number of immobile objects which are captured when a player wins a tactical mission. Then they can be sold for money or researched to unlock further research, or at least get some flavor text and score. But there are at least three exceptions.

Alien Reproduction


A valid base inventory object and research topic, with Ufopedia text and graphics available, but the Battlescape tile that would yield it after a mission is not implemented. The research text reads:

English: These chambers contain alien foetuses. The design of these containers seems to suggest that the aliens which use this process rely completely on laboratory reproduction. The rich nutrients ensure rapid development of the foetus. This factory line system could generate thousands of alien clones in a short space of time. The process could be easily adapted for human reproduction, or alien-human hybrids.

French: Ces chambres contiennent des foetus aliens. La forme de ces containers semble suggérer que les aliens qui utilisent ceprocédé dépendent totalement de la reproduction en laboratoire. Les aliments riches assurent le développement rapide du foetus. Cette reproduction à la chaîne peut générer des milliers de clones aliens en très peu de temps. Le procédé pourrait facilement être appliqué pour la reproduction humaine, ou pour des hybrides aliens-humains.

German: Diese Kammern enthalten außerirdische Föten. Die Konstruktion dieser Behälter deutet darauf hin, daß die Außerirdischen, die diese Methode benutzen, zur Fortpflanzung auf Labore angewiesen sind. Die reichen Nährlösungen garantieren die rasche Entwicklung des Fötus. Diese fabrikmäßige Aufzucht könnte innerhalb kürzester Zeit Tausende von außerirdischen Klonen erzeugen. Der Prozeß kann leicht auf die Fortpflanzung von Menschen oder Mischformen angewendet werden.

The item does not trigger any lines of research and is there solely for flavor, just like half a dozen other "alien research" items. There are various fan speculations to as why it was not included. Interestingly, this idea is revisited in X-COM: Apocalypse as "procreation parks" derived from the invaders' technology and being the preferred way of reproduction for humans in the 2080s.

UFO Construction

In the sequel X-COM: Terror from the Deep, the "USO Construction" item is captured in downed USOs, and the player needs to study it to be able to research craft based on alien technology... but in this game the UFO Construction item has no relation to UFO Construction research. The research is unlocked by a combination of topics on UFO components. However, the base inventory item still exists and can be sold, if it's added by editing a save game.

Alien Habitat

Research item, text, and graphics are absent. Battlescape tiles can be altered to yield this base inventory item after a mission and it can be sold, but not researched. Fans speculate that this item together with "Alien Food" may have been intended for researching Alien Containment facility, but in all versions of the game Alien Containment is already buildable from the start.

Unused Ufopedia Text

Aircraft weapons lack description texts in the game, but the strings are present in the ENGLISH.DAT, FRENCH.DAT, and GERMAN.DAT files. The first five obviously correspond to Stingray, Avalanche, Cannon, Fusion Ball and Laser Cannon. The remaining weapon is Plasma Beam, which doesn't fit the remaining description.







Unused Graphics

Unused Terrain Tiles

The terrain in the game is generated through the following process:

  • The actual tile graphics are stored together by theme in a compressed file with the extension .pck
  • A .tab file tells the game what graphics are what in the .pck file.
  • Sets of tiles and their properties (i.e. animation frames for and destroyed versions of an item) are stored in .MCD files.
  • Groups of tiles are assembled into templates called .map files
  • The game generates actual levels by assembling random .map files into a whole game map.

Therefore it is possible that there are graphics in .pck files that are not defined in the game's .MCD files, and even if they are then they may not be actually be used in any map files in the actual game. Based on the filenames of the .MCD and .PCK files used by the game, some are at least the second iteration of some sets of graphics (e.g. U_EXT02.MCD, U_WALL02,MCD), and the first iteration is not shipped with the game. The maps in the cut map section clearly use tiles sets not shipped with the final game.

(Source: UFOPaedia.org)

The Interceptor and Firestorm both have MCD and pck files created (inter.pck/mcd and fires.pck/mcd) for them to be shown in the Battlescape like the crew-carrying aircraft (Skyranger, Avenger, etc). However, the tiles used are just copies of the Skyranger and Lightning, so these are presumably just placeholders that were never populated/needed.

The file U_DISEC2.MCD is used for the inside of UFOs like the Harvester, and as its name suggests, consists of the tile graphics for the dissection tools (and dissected cow) these craft contain. However, checking the corresponding U_DISEC2.PCK file shows there are more tiles present that were never defined in the .mcd:

  • Some kind of two-part sink or trough in which the unfortunate cow's blood and organs are pooled inside. This and the metal grate are depicted in the UFOPedia image for "Alien Surgery" in the final game (see right).
  • A metal grating, presumably for blood to sluice through from the dissection table...
  • Destroyed versions of the two dissection robot arms.

Oddly the PC Format demo of the game includes an earlier version of U_DISEC2.MCD that does have these tiles defined as part of the tileset, so they must have been cut from the game at some point.

Unused Item Graphics

The original UK demos of the game featured a number of cut items and item graphics that are mostly purged from the final game. However, the FLOOROBJ.PCK file (which contains the graphics used for inventory items resting on the floor in the game) still has the graphics for several of the cut items present:

Graphic Item Name Notes
UFOEU-GXPsiamp.png Psi-Amp This is the ground graphic for the original design of the Psi-Amp as used in the demo. It cannot be seen in the final game as the alien design seen in the demo is now used there instead
UFOEU-GStunGasGren.png Stun Gas Grenade The ground image of the cut (and useless) Stun Gas Grenade weapon found in the demo
UFOEU-GPlasmaClip.png Plasma weapon Clip This actually is used in the final game, but the behaviour around it is of note. In the demo this graphic (and its corresponding larger detailed inventory version) was used for all plasma weapon magazines laying on the floor. In the final game they each have unique designs for the inventory screen, but if thrown on the ground still use this shared generic design as a holdover from the demo

Unused Interface Graphics


The file SPICONS.DAT contains only two icons used for special buttons in the Battlescape. The first is the Blaster Bomb Launcher fire graphic. The second is an unused "Psi" button. It's not clear what this was for as psi skills are used via the Psi-amp item. Either Psi abilities orignally didn't need an item, or this would be how you access the powers of mind-controlled psi-capable aliens. (Since they don't use Psi-Amps.)

(Source: UFOPaedia/Bomb Bloke (spicons.dat graphic rip))

Sound Changes

The patch to DOS version 1.4 radically changed many sound effects in the game. The rationale for this according to communiques from Microprose on Usenet at the time (see versions listing above) and the larger file size of sounds used seems to be to use higher quality samples. The lack of an option (until OpenXCom...) to change between soundpacks was not as well-recieved, however. Below is a comparison table of which sound effects were changed between versions. Sounds not listed here remained the same between versions:

Sound Effect DOS V1.0 DOS V1.4
Muton death scream
Celatids death scream
Snakeman/Silacoid death scream
Ethereal/Chryssalid death scream
Sectoid/Floater/Reaper death scream
Flying movement
Celatid move
Item Drop
Item Throw
Hovertank/Cyberdisk move
Reaper/zombie attack
Chryssalid attack
Silacoid attack
Celatid attack
Rocket launch
Blaster bomb/stun launcher

To accommodate the above changes, the game's underlying sound system was also changed. In versions before 1.4, all samples are assumed to be 8000hz, and do not have any kind of sample header (because it would be ignored and the sound played at 8000hz anyway). Version 1.4 made it so that higher sample rates could be used, and the game would actually now check the header of a sample to know what sample rate to play it at.

It should be noted as well that the Windows Collector's Edition of the game also removes all sound effects during the intro animation, with only music played instead.

Unused Map Blocks

To do:
Find right MCD combo to get picture of Temp1.

Tactical maps are randomly assembled from pre-made blocks. Maps (3D arrays of tile indexes, usually 10×10×3) of each block are stored in MAP files, and tiles they use are defined in MCD, PCK, and TAB files. A map can use multiple tilesets and what corresponds to what is set in the engine.

There are several MAP files that are not used by the engine. There is no way to tell what tile sets they were made for, but fans have figured out reasonably good guesses: https://www.ufopaedia.org/index.php/Talk:MAPS


A 32×48×3 map with several blocky human buildings, but with alien gravity elevators.

The file contains several extra bytes at the start, and has to be manually edited for MAP editing software to accept it. The polar terrain was chosen because only it has puddles; the original intention is unknown. The block is far larger than any other terrain block, and cannot be combined with them as it is because everything else has length and width in multiples of 10. There is no room to place X-COM craft and no exit grid, thus the block cannot be used as the only block for the mission. It's speculated by fans that therefore this and the MAP4 may in fact be special base levels for the cut Men in Black enemies.


A 32×48×3 map of a single large building in the same style. This seems to in fact be the underground counterpart to MAP3. The white snowy ground should in fact be rock walls like in an alien/X-Com base, and therefore the central area is likely a grav lift in. The second level is a totally flat surface which seems to have been a solid ceiling/ground.


The first of several interesting pyramidical ships. The tilesets used here were created by fans based on those of the Mars tileset, as the original files are missing from the game. The purpose of these different designs is unknown, whether they were an early attempt at getting around the difficulties of using curved surfaces in the game, or if they would be for a specific species of alien, or to simply tie into the pyramids on Mars myth visible in the game's final level.

A 10×20×4 map with two pyramids linked together, with alien technology inside. Apparently the pyramid version of the Abductor ship.


A 20×20×4 Dome-shaped UFO assembled out of pyramids. Clearly the pyramid equivalent of the Harvester ship. Note the red squares with numbers in are unknown object tiles that have no equivalent in the final game's graphics.


A 10×10×4 pyramid-shaped scout UFO.


The Temp maps seem to be exactly as their name suggests - work in progress versions of level blocks that had not yet been moved to their final .MAP file yet.

A 10×10×1 map that's an early version of the bottom level of the final URBAN17.MAP.


A very simplistic 10×10×1 design similar to the medium scout UFO.


A 20×20×1 map that's an early version of the middle level of URBAN08.MAP.


A 20×20×1 map that's the same as TEMP2.MAP, but without stairs and with a table and chair placed.


A 10×10×2 map that's a smaller version of the medium scout.


A 20×20×2 map that's a smaller version of the abductor.


A 2×2×3 UFO smaller than Small Scout.

This map uses unused tiles from files UFO1.MCD, UFO1.PCK, and UFO1.TAB - same as for the Small Scout. Unlike the Small Scout, however, this ship has no gravity lift and no interior. Due to the way the game calculates the number of alloys the player gets from a recovered UFO based on the number of tiles it occupies, this unused model is actually too small to reward any.

(Source: UFOPaedia.org, screenshots, MCD recreations and discoveries)

Unused Mechanics

To do:
Other unused game mechanics implemented in the engine, but not used by existing resources and uncovered by altering files and reverse engineering. Melee combat too.

Fire and smoke area effects use similar mechanics, but the engine allows four more types of smoke-like effects. There are no resource files for them and nobody knows what they were going to be. They are speculated to be gas weapons like in Apocalypse.

There are four unused types of grenades. Again, speculated to carry the four unimplemented types of smoke-like weapon.

Melee Combat


While enemies engage in melee combat and X-COM can use the Stun Rod in the final game, it seems originally melee combat was to be a much more important mechanic. A picture in the manual (see right) shows that until relatively late in development it was possible to use at least the standard issue Rifle (and likely most other weapons) in melee as well as a firearm. Thanks to a glitch in the game it is possible to stack two weapons in one hand to merge their abilities, and doing so with the Stun Rod essentially unlocks the old melee functionality for all objects. Rather than stunning, this uses the old damage values that were configured for each item before melee combat was cut, although many items don't seem to have had meaningful values here (because they were not intended for use this way), causing them variably either to be useless or devastating in their damage output.

It seems melee damage would only do actual hit point damage (i.e. it would not stun enemies). The game actually has a hidden Melee Accuracy stat for all soldiers [7]. This shows that originally it was possible to miss with melee attacks. The stat actually increases in value in the final game with use of the Stun Rod, like other soldier stats. However, it has been found that in fact the game is hardcoded to completely ignore this stat, all melee attacks with the Stun Rod always have 100% chance to hit, so can never miss.

In the early demos of the game, the Stun Rod's melee attack is called "Hit". It seems this was an earlier generic attack name that was used by all melee weapons, that was changed to "Stun" once the Stun Rod became the only X-COM melee weapon left in the game. Due to the release date of the demos (February 1994), this must have been a very late change.

(Source: UFOPaedia )


  1. David L Craddock (2021), Monsters in the Dark: The Making of X-COM: UFO Defense, P142
  2. UFO: Enemy Unknown game versions, Strategycore.co.uk
  3. Robert Ruth Usenet Post - comp.sys.ibm.pc.games.strategic, March 1995
  4. Detonate Usenet Post - comp.sys.ibm.pc.games.strategic, September 1999
  5. Scott Johnston Bloodwych Review - Amiga Games Database, October 2000
  6. Matt Simmons Youtube comment - Youtube, 2013
  7. Melee Accuracy - Ufopaedia.org