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Proto:X-COM: UFO Defense

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This page details one or more prototype versions of X-COM: UFO Defense.

There are multiple Pre-Release demos for the game, two for the original release in the UK, and another for the later American release. There is also a later German demo based on the second UK pre-release.

PC Gamer UFO: Enemy Unknown Pre-Release Demo

This was a special demo created exclusively for the British PC Gamer magazine, and released on the cover disk of their 5th issue from April 1994. The demo of course uses the original UFO: Enemy Unknown name for the game. It also features a mixture of soldiers with differing weapon and armour types, with each soldier named after a PC Gamer member of staff, including future Star Wars writer Gary Whitta.
While the demo was released in April 1994, filestamps show many of the files (including the PC Gamer specific intro slides) were created in February of that year. The demo consists of a night time terror mission as X-COM do battle against Chryssalids and Snakemen. If that wasn't enough of a trial by fire, the demo doesn't even give you any Electroflares!
The map is a set level, and not random. It consists of the Skyranger parked near some parkland cut off from the main area by a road. Across to the East there is an apartment building and a warehouse full of Chryssalids.

There are many changes visible in the demo, and a lot of cut content in its files.

Soldier Loadout

The player is given a fixed squad of 6 X-COM soldiers, all at Rookie level. Their composition seems to be deliberately designed so the player can test out a range of different weaponry and armour, and also gives some nudges towards re-organising the squad for a more optimal loadout. For example, the soldier with the lowest strength stat has the Heavy Cannon and loses Time Units each term due to being over encumbered. So too another soldier starts with no weapon, but there is a spare Laser pistol in the SkyRanger. The below are the only X-COM weapons/items in the demo, however it is possible to hack in more items in the demo code into the mission.

Soldier Name Armour Weapon
Gary Whitta Power Suit Rifle, clip, and grenade
Chris Buxton Power Suit Rifle, clip, and grenade
Andy Butcher Power Suit Heavy Cannon (loaded with AP rounds), HE Rounds, grenade
Maryanne Boothe Personal Armour Laser Rifle, grenade
Dan Goodleff Personal Armour Heavy Laser, Grenade
James Blackwell Personal Armour Grenade

Interface Changes

Equip Screen

The demo features an early version of the initial equip screen and also the in-game inventory screen(s).


  • There is no unload ammunition button on the equip screen. The game provides the player with some HE ammunition for the Heavy Cannon, but without the button there is no way to use this until the original AP magazine has been expended.
  • There is also no "OK" button on the equip screen, to exit the player must press the right mouse button. Furthermore, the change soldier button is missing in-game, so each soldier's inventory must be viewed one by one by changing to that soldier in the Battlescape first.
  • The button to switch between different pages of items on the floor is also missing, meaning items off screen are inaccessible.

Motion Scanner Screen


A simpler brown coloured Scanner screen is used in the demo. This looks superficially like the early Map screen design seen in the Pre-Release coverage. The map screen in the demo is identical to the final game's, however.

Medi-Kit Screen


As with the Motion Scanner, the Medi-Kit has a similar crude early graphic when used.


  • As seen in many of the pre-release screens, there is no visible ammunition counter to show how many rounds are left in a magazine. Therefore the only way to know how many rounds are left in a loaded weapon (or even if the weapon is loaded at all), is by going to the inventory screen and clicking on the weapon.

Graphical Changes

UFOEU-beta firing animation.gif

  • Totally different bullet impact effects. The actual projectile graphics appear to be the same, but when a target is hit (be it an enemy, X-COM or the scenery), a strange firework like effect spreads out briefly from the impact point. This of course is not the behaviour of the final game.


  • Smoke has a simpler graphic that is not animated
  • There are no fire sprites displayed in the demo. Explosions create smoke and damage the ground, but there are no flames. Oddly the graphics are present in the files.
  • Snakemen do not have graphics/animations to carry weapons in the demo. While certainly actually possessing weapons, these are not visible in their hands and they walk around using the disarmed graphics they use in the final game after recovering from being stunned. Checking the .pck files it seems the weapon carrying graphics simply weren't drawn yet. The Snakemen also seem to be armed with Plasma Pistols.
  • No female X-COM soldier graphics in-game yet. There is a single female soldier in the demo, but a male character model is used. Checking the actual .pck files that come with the demo show there are no female heads present, so either they were left out to save space, or had not been implemented yet.
  • While none of the soldiers in the demo have Flying Suits, investigating the .pck files shows the in-game graphics for these are present already.
  • Only female civilians are seen in the map.


  • There are no X-COM soldiers in an unarmoured state in the demo. However, hacking the files to make a unit unarmoured reveals that the demo uses the early bearded male X-COM soldier Graphic! This can be seen in many of the early previews of the game and shows they must have come from a similar build.
  • BLANKS.PCK is also an early version. It is missing the burnt ground tile that the final game contains. This means that if ground tiles get damaged in the demo they often simply turn into dark black squares.

(Source: UFOPaedia/Bomb Bloke (firing graphic, misc info))

Item Related Changes

  • Laser Rifles are called "Laser Guns".
  • Stun bombs are called "Stun Missiles".
  • All plasma weapons have the same graphic for their ammunition, an odd boxy thing that is not in the final game. They are still unique ammunition types; they just use the same graphic.
  • If hacked in, the Blaster Bomb launcher looks the same as in the final game in the inventory screen. However, picking it up uses a different grey palette to the one in the final game. Firing it seems to work as per the final game, only with the demo "firework" effect on impact as with other weapons.
  • The Mind Probe is present in the demo files and looks and behaves exactly as in the final game, only no sound effect is played when used on a target. Its palette also becomes darker when equipped like some other objects in the demo. If thrown on the floor it takes the appearance of one of the unknown cut objects (see item graphic table). This suggests the unknown graphic was actually either an early version of the mind probe, or the alien equivalent of it.
  • Medi-kits are present in the game's files and seem to work.
  • Motion Scanner -present in the game's files and works as per the final game.
  • Psi-Amp - This has a completely different design to the final game, appearing as some kind of combined helmet/gas mask equipment a soldier must wear, rather than the gun-like appearance of this item in the final game. While it appears to work (if used by a soldier hacked to have psi attributes), APs are deducted but no actual effect seems to occur on enemies regardless of whether panic or mind control is used. It's likely the psi mechanics simply weren't implemented yet.
  • Plasma Rifle - As with the Blaster Bomb Launcher, this looks identical to the final game in the inventory screen, but actually equipping it displays it using a darker palette
  • If hacked into the game, stun rods can be equipped, and if used against a target there is a "Hit" attack option rather than "Stun" as in the final game. Using it on an enemy shows a melee attack impact, but has no other result. Further testing with the Small Launcher and Mind Probe shows stun damage does not exist in the demo code, making both stun weapons useless.
  • There is a cut grenade item, a "Stun Gas Grenade". It has a similar icon to the smoke grenade. It cannot be primed, and does not go off when thrown, so is useless.
  • Examining the obdata.dat file shows that there is also the item "Gas Grenade 2" listed, but this does not seem to exist as a useable item in the demo.
  • There's also a "Medium Rocket" defined for the Rocket Launcher, when in the final game it only fires small, large or incendiary rockets. The final game graphics are still in use, with the medium rocket using what is the large rocket in the final game, and the incendiary rocket graphic used for the large rocket. Firing these munitions, they do indeed have slightly larger blast radii to each other.
  • The demo does not give you Electroflares to assist with seeing at night. Checking the obdata.dat file shows they are not defined here, so possibly they still did not exist at this point of development.
(Source: UFOPaedia/Bomb Bloke)

Item Graphical Changes

Items with either graphical changes from the final game, or those that were cut entirely

Graphic Item Name Notes
UFOEU-PDemoHCannon.png Heavy Cannon The Heavy Cannon has a different barrel design to the final game
UFOEU-PDemoPlasmaClip.png Plasma [X] Clip All Plasma weapon magazines use this single graphic in the demo
UFOEU-PDemoElerium.png Elerium 115 A totally different design for the rare alien element
UFOEU-PDemoSGasGren.png Stun Gas Grenade A similar design to the smoke grenade for this useless cut item
UFOEU-PDemoAPsi-Amp.png >>> UNDEFINED <<< A useless item that uses the graphic for the final game's Psi-Amp. Perhaps originally intended as the alien equivalent to the human Psi-Amp design?
UFOEU-PDemoPsi-Amp.png Psi-Amp A very different early X-COM tech design for the Psi-Amp item
UFOEU-PDemoDBB.png Blaster Bomb Launcher When equipped on a soldier, this darker palette is used for the item
UFOEU-PDemoDPR.png Plasma Rifle When equipped on a soldier, this darker palette is used for the item
UFOEU-PDemoDMindP.png Mind Probe When equipped on a soldier, this darker palette is used for the item
UFOEU-PDemobigobs 40.png Unknown A graphic for presumably some kind of projectile, similar to the Blaster Bomb design. Only the image file remains in the demo. Could this be the mysterious Gas Grenade 2? Filename bigobs_40.pck
UFOEU-PDemobigobs 42.png Unknown A graphic for an unknown object that looks like a lightbulb taking off. Only the image file remains in the demo. Filename bigobs_42.pck
UFOEU-PDemobigobs 43.png Unknown A graphic for another unknown object that looks like a helmet with an eyeball underneath. Only the image file remains in the demo. Filename bigobs_43.pck
UFOEU-PDemoAMP.png Unknown What appears to be the ground object graphic for the item above, from the file FLOOROB.PCK. This takes up the space used by the Mind Probe in the final game, and is displayed if that item is thrown on the floor in the demo. Perhaps this was an early design or equivalent alien version of the Mind Probe?
(Source: UFOPaedia/Bomb Bloke (Graphic rips))

Gameplay Changes

  • The demo features very different damage values compared to the final game. Snakemen take a number of hits to kill, even from Laser Rifles.
  • Primed grenades explode when their timer reaches zero, regardless if they in an soldier's inventory, unlike in the final game.
  • The demo defaults to the awkward "Trigger scroll" screen scroll setting.
(Source: UFOPaedia)


  • Grenades make various gun firing noises when thrown.
  • Oddly Maryanne Boothe (the only female soldier in the demo and umm, one time Art Editor of PC Gamer) appears as a male on the initial equip screen. However, viewing her inventory once the game begins shows the correct female picture.

Changed Demo Map

The demo begins with with screens of a UFO being detected by a Brazilian X-COM base and then the shooting down of that UFO over the Amazon rainforest. The text at the end of the demo also talks about recovering a UFO as if it were intended to follow a UFO recovery map. This is all elementary however: the slide just before the Battlescape part begins explicitly says the mission is going to be a UFO recovery in the Amazon jungle. It's quite surprising that the demo is actually a city terror map, then.
In fact this original theme is present in the PC Format magazine demo released at the same time, which consists of UFO recovery mission against Sectoids in a Large Scout UFO in the jungle. What makes this clearly last minute change odd and risky is that the Sectoid spritesin the other demo are much closer to the final game's than the unfinished Snakemen ones and actually have animation frames for holding their weapons. It's surprising then that the demo in fact completely abandons this original concept.

Presumably it was changed at the last minute either to differentiate it from the PC Format demo (the PC Gamer one is highly customised and unique compared to the more generic demo PC Format got) or because the more exciting Snakemen/terror mission assets were created, even though they were unfinished. After all, what could be a more nail biting introduction to the game than a night time terror mission against Chryssalids? Clearly this demo was considered the better of the two, as the American demo is based on this and not the more coherent PC Format jungle demo.

The jungle mission briefing slide is corrected in the later American demo.

Slide Differences

The static slides introducing and ending the demo are named screen00-22. However, images 5, 7, 8, 12, 15, and 17 are unaccounted for. Possibly there were originally even more comprehensive instructions planned?


  • As with the early Pre-release footage, the Geoscape screen is shown with a "Highlight" button instead of one for Funding.


  • Different stats shown for the Heavy Cannon in ufopedia screen compared to final game.


  • The Firestorm is shown as having 3000 fuel capacity. In the final game this is only 20, so possibly there was an entirely different metric for measuring fuel at this stage.

Unused Sounds

The demo has a different sound file setup than the final game, with all samples as loose files in their directory rather than in a .cat file as in the final game. They also have specific names rather than numbers. There are samples from the intro and Geoscape that are not used by the demo at all, and the following files are not preset in the final game.

These are samples of a woman with a British accent that seem to be related to the interception minigame, presumably they would be combined to report on the action as it occurred ("UFO Damaged", "Interceptor Damaged"). While the "Damaged" sample is stored as 8000hz as per the final game's samples, the other two seem to be of a lower sample rate. They are recorded here at 4500hz as this seems to be around the correct speed. They are very low quality samples.

Sample Filename Notes
dam.sam A woman saying "Damaged"
int.sam A woman saying "Interceptor"
ufo.sam A woman saying "UFO"

Unused Files

There are several unused files in the GEODATA directory marked with ".old" file extensions.

  • BIGLETS.OLD This is an old version of the main large font of the game.


  • SMALLSET.OLD This is an old version of the small font used in menus, etc. This and the above big font appear to be the ones visible in the very early screenshots seen in the Joystick magazine coverage of the game. They cannot be substituted back into the game as they are too different from the format of the final fonts. Oddly these both date back to 1989, before the game was even started.
  • LOFTEMPS.OLD An old version of the Line of Fire Template. This is what is used to calculate the 3D shapes of 2D objects when projectiles are fired across the map. This old version is 50% larger than the final file and seems to store the data in a different way.

Concept Art


Inside the directory UFOGRAPHS is a file called icons4.lbm. This seems to be a very early concept art picture of the game's Battlescape interface! Most of the buttons roughly line up with commands from the final game, although the "2D/3D" button is interesting and may have been to switch between an isometric and flat 2D view somewhat like Laser Squad's firing mode. In fact it might even be possible that this image is from the Laser Squad 2 period of development (it has 256 colours so can't be from an Atari ST game). It's dated from July 1992 which seems quite late for that to be the case, however.

Debug Mode

The demo includes disabled debug code for the game that can be re-enabled by editing the executable. If position 0x5D66E in ufo2exe\ufo.exe is set to 01 with a hex editor, the debug mode will be enabled. Once enabled the following occurs:

  • Removes fog of war and shows all map tiles.
  • The lighting system is disabled, setting the whole map to maxium brightness even at night.
  • Does NOT show enemies or civilians out of line of sight on X-COM turn.
  • The enemy turn is fully revealed, showing all enemy actions. While the AI is performing its actions a debug display at the top right describes what each enemy is doing (walking to point, firing on point, etc). Once all moves are complete, the enemy turn continues but the player has control and can inspect all enemies as if they were part of the X-COM team, and can even move enemies and perform actions if they still have TUs left. Inventories and stats can also be viewed. Once the end turn button is pressed, the player gets control of X-COM again.

It's not clear if there are other functions accessible from this mode.


Also included with the demo is the file descurs.pck. This is not present in the final game, and is a series of mouse cursor icons clearly from some kind of debug mode. Based on the options it's likely used for setting AI routing paths through map segments. It's not known if there is some way to enter this mode in the demo or if this is a leftover from some kind of external editor program.

The executable also contains the following text strings used by the debug mode:

Patrol xSniper iCombat eEscape 
Guard teGoUfo ntFinding Route 
Set Patrol Point otpMoving tFiring nEvaluating mode Final Facing er Attack Attempt oFind Fire Point Select Target   Find Cover pPartial Cover 
(Source: UFOPaedia/Bomb Bloke/Volutar (debug mode activation instructions))

PC Format UFO: Enemy Unknown Pre-Release demo

This was a different demo of the game, released at the same time on the cover disk of PC Format issue 31 from April 1994. This is clearly the original design of the demo, seeing as it's a UFO recovery mission that takes place in a jungle as per the introductory slides of the PC Gamer demo. The base files the two versions share are identical, but this demo includes jungle and UFO graphics tiles that were not present in the PC Gamer city based demo. The executable is slightly smaller for this release and is timestamped from two days after the PC Gamer release.
Strangely, the pictures on the box of the American release of the game (X-COM: UFO Defense) are all taken from this demo.


The jungle map terrain is numerically the first tileset listed in the final game's files (so was likely made first - something confirmed by the weird MOC1.LBM file that is a picture of the jungle terrain tiles used solely for setting the correct palette in all versions of the game), and this along with the fact that the Sectoid's graphics were mostly finished suggest they were probably the most complete and therefore logical best bets to include in a public demo.

Soldier Loadout

This time the soldiers have a totally different loadout, and use generic games chosen from the game's random pool. They are not named after magazine staff. None are armoured, so you get to see the early soldier graphic with their lovely beards! Including what is clearly supposed to a woman with one...

Soldier Name Armour Weapon
Igor Petrov None Rifle, clip, 2x grenades
Masanoro Okamoto None Heavy Cannon (loaded with AP rounds), AP Rounds, HE Rounds, 2x grenades
Neil Sharpe None Auto-Cannon (loaded with AP rounds), AP Rounds, HE Rounds, grenade, smoke grenade
Karin Faerber None Laser Rifle, grenade
Henri Revenu None Pistol, Grenade
Tom Carr None Laser Pistol

Misc Changes

  • Sectoids bizarrely make the tank explosion death sound when killed.


  • The UFO has been shot down, and the UFO Power Supply has exploded. However, unlike the final game where this usually casuses cataclysmic damage, the UFO is completely intact and just has a little smoke in the room at mission start. All aliens are also still alive.
  • While the buttons at the bottom of the control panel used for reserving Time Units while moving look the same as the final game, they don't actually work and cannot be clicked on. They do work in the PC Gamer demo, however.

Tile Graphic Changes

The file U_DISEC2.MCD is an earlier version that includes cut tile graphics for a kind of basin full of blood, a metal grate in the floor, and destroyed graphics for the robotic dissection arms. These are present in the final game files but unused as the MCD has had them purged from its contents.

Debug Mode


As in the PC Gamer demo, there is a debug mode present in the code. To enable it, hex edit UFO.exe at address 0x5BD85 to have the value 01. It seems to behave identically to the debug mode in the PC Gamer demo.

X-COM: Terran Defense Force Demo


A reworked version of the PC Gamer UK demo, but using the assets and code improvements of the now final game, specifically of version 1.2. An extremely important demo that was instrumental in the game's success in the American market, when it was released in May 1994. Hosted online for download by the likes of AOL[1], it quickly put the otherwise mostly ignored game into the spotlight in the USA through sheer word of mouth. File stamps in the demo date back to April 1994. Strictly speaking this was still a pre-release demo as it was targeted at the USA where the game was not out, whereas it had already been out for two months in the UK and Europe.

The original release of the demo was in a zip file called "xcomdemo.zip"[1] that contained a readme file and a further self-extracting archive.

USA Demo Readme

Note the entirely different early name for the game and that X-COM is frequently referred to as "XComm".

     ******************  X-COM: Terran Defense Force  ******************

	MicroProse Presents
			  X-COM: Terran Defense Force

	MicroProse is planning to release X-COM: Terran Defense Force in 
	the United States. X-COM: Terran Defense Force is a futuristic 
	game of strategy and tactical combat in which the player 
	defends the Earth from alien invasion.

	The game involves the player at two different levels: 
	In-depth strategy as the player controls the operation 
	of bases that he builds all over the World to cope with 
	the alien threat and tense "seek and destroy" tactical 


	It is the year 1999. Sightings of alien craft have 
	increased dramatically throughout the World. All attempts 
	at peaceful communications have been met with hostility. 
	Reports arrive daily of kidnappings, murder, terrorism, 
	and killings of cattle and domestic animals.

	The nations of the world have decided that they must join 
	forces to combat the alien threat. To this end, a special 
	defense force named XComm is set up with collective funding 
	from all countries.

	You are the commander of XComm.

	Game Features:

	-  In-depth strategy involving scientific research, weapons 
	   production, resource allocation, and expansion through base 

	-  Tense tactical gameplay with "Aliens" search-and-destroy 

	-  Non-linear gameplay for extended play.

	-  Popular "Manga" look and feel to graphics.

	-  Numerous mission types: Intercept, Seek-and-destroy, 
	   Base defense, etc.

	-  Differing terrain according to mission location: 
	   Snowscapes for Arctic  locations, Cornfields for the 
	   midwest, Cityscapes, etc.

	UFO: Enemy Unknown, from MicroProse, is expected to release 
	for IBM-PCs and compatibles in June. 

To load the X-COM demo:

   Change your current drive to THIS floppy drive and type in:

	XCOM -d destination

   "destination" is the hard drive where you want X-COM loaded.
   For example, if you type "xcom -d D:\", the demo will be loaded
   into D:\XCOMDEMO.  The colon and backslash after the drive letter
   are REQUIRED.

To run the X-COM demo:

   Change your current drive and directory to the XCOMDEMO
   directory from above, and type "XCOM".

	   Copyright 1994 by MicroProse Software, SH, Inc.

Soldier Loadout

The soldiers you are given in this newer demo have been slightly changed from the first one. Soldiers now have names from the final game's automatically generated pool, unlike the real life names used in the PC Gamer demo. Once again a soldier has an suboptimal weapon for his build, and you get to play with an Autocannon and some smoke grenades. However you now also get one less Power Suit in the team. There are also two Electroflares in the SkyRanger.

Soldier Name Armour Weapon
Manfred Geisler Power Suit Rifle, clip, grenade, smoke grenade
Paul Blake Personal Armour Heavy Cannon (loaded with HE rounds), HE Rounds, grenade, smoke grenade
Sylvie Lecointe Personal Armour Auto Cannon (loaded with incendiary rounds), incendiary rounds, grenade
Manfred Unger Power Suit Laser Rifle, grenade
Evelyn Nash Personal Armour Heavy Laser, Grenade
Ed Carr Personal Armour Laser Pistol

Changes from PC Gamer Demo

  • Largely the same map as the PC Gamer demo. However, where there was simply parkland at the most North Westerly part of the map, there is now a house there. Similarly, the apartment building to the South East is now a retail area.
  • There are now two female members of the squad, and the demo actually includes female Battlescape graphics as well.
  • Fire and smoke are now the same as in the final game, and are also animated.
  • There are now Electroflares and incendiary ammunition, so the map can be illuminated by the player.
  • Equip screen is identical to the final game.
  • Weapons fire using the same effects as the final game.
  • Laser Rifles are now named as such, and not called "Laser Gun" anymore. Stun Bombs are also no longer called "Stun Missiles"
  • obdata.dat contents are now mostly the same as the final game. The Gas Grenade entries have been removed.
  • Jungle map tiles and Sectoid related files are not present in the demo.
  • All weapons seem to look and behave exactly as the final game ones now.
  • Hacking in a Medi-kit and using it freezes the game as the needed graphic for the Medi-kit screen is not included with the demo. It's possible to continue to a corrupt screen and use it,however.
  • Hacking in the Motion scanner and using it completely crashes the game as there are none of the needed screen graphics for it in the demo files.


  • If a Psi-amp and a psi adept soldier are hacked into the demo, psi abilities work as per the final game
  • Enemy AI (especially Chryssalids) seems more aggressive.
  • The strange darker palette effect for some of the items when equipped is now gone
  • Snakemen now have weapon carrying graphics and are armed with Heavy plasmas and alien grenades
  • Only male civilians are seen in the map

Introduction Slide Changes

Most of the slides are identical to the first game, but with all references to PC Gamer magazine removed. There are the following important changes, however:


  • The title screen of the demo calls it X-COM: Terran Defense Force. This seems to have been one of many attempts at renaming UFO: Enemy Unknown for its USA release by the American Microprose/Spectrum Holobyte management.


  • Introduction slide now changed to reflect the fact the demo is a terror mission, not a UFO recovery in the Amazon jungle as per the briefing slide in the first demo.


  • A further attempt at renaming the game is visible on the slide after the mission is complete, where the game is now referred to as X: Enemy Unknown.
(Source: UFOPaedia/Bomb Bloke)

German UFO: Enemy Unknown Demo

A peculiar demo that was released around July 1994 in Germany. Timestamps on files vary, with some as late as May 30 of that year, while the rest line up with those of the original British demo, generally from February 1994. While the game had been out for some time at this point it still uses the ancient pre-version 1.0 build of the game.

  • The slides for the Heavy Cannon and Firestorm now have corrected values that match the final game.
  • Slides (and everything else) are naturally in German
  • There is an extra slide compared to the other demos, that shows the UFOPedia screen for the Interceptor.
  • The debug mode is still present, with the same offset as the PC Format demo it is clearly based on.


  1. 1.0 1.1 Paul L Fincke usenet post - comp.sys.ibm.pc.games.strategic, May 1994