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1001 Video Games

UFO: Enemy Unknown appears in the book 1001 Video Games You Must Play Before You Die by General Editor Tony Mott.

Difficulty Level Bug

DOS version of the game has a bug in the difficulty settings. Regardless of which difficulty level you choose, you always start at the easiest level. Surprisingly, the official patch of the game does not correct this problem. However, there is an unofficial patch available for solving this issue. Problem is also solved in The Collectors Edition Windows port (also commonly known as UFO Gold or CE).

The game contains many different other bugs. All of them are gathered on UFOPaedia.

Cancelled successor

A new version of the X-COM series dubbed X-COM: Genesis, focusing on some of the gameplay features found in the original, was in production at Hasbro/Microprose in 1999. The project was cut during mass-layoffs for the company.

CD-ROM version

The CD version may include a partial install version and a full install version, depending on which CD you got. The partial install version leaves some datafiles on the CD to save disk space. However, the "full install" version is also on the CD in the HARDDISK directory.

The CD version of the game for DOS was not different from the original floppy one. However it contained animated introduction (the very same which was later used in Amiga CD32 version and (from the Playstation version) and the executable file was patched and some bugs were eliminated.


Jullian Gollop, designer of X-COM: UFO Defence tells how X-COM was created (taken from the Mythos Games web site):

We showed a demo of ‘Laser Squad 2’ on the Atari ST to Microprose in 1991. The idea was to produce a sequel to ‘Laser Squad’ but with much neater graphics using an isometric style very similar to Populous. They liked what we had done so far, but they explained that they wanted a ‘big’ game. I said "what do you mean by ‘big’" and they said "well, you know – BIG". They also said that it had to be set on earth, like Civilisation or Railroad Tycoon, because people could relate to it much more. So we went away, scratched our heads and thought about it. Then we came up with the idea of adding on a grand strategic element to the game, very firmly set on earth, in which the player managed an organisation that defended the planet against UFO incursions. I bought quite a few books on UFOs for research purposes so that we could give the game an even more ‘authentic’ basis.

The project started reasonably well with myself and Nick designing and programming, while the art was to be done by John Reitze and martin Smillie at MicroProse. Soon we had some problems because Microprose did not understand our game design and they asked for clarification. Several documents later we were not much better off and I had wasted a lot of time. Certain creature types were removed, including the ‘Men In Black’ and others added. Then the whole project was nearly axed when MicroProse made some cutbacks due to financial difficulties. Everything proceeded reasonably smoothly for a while until Spectrum Holobyte acquired Bill Stealey’s shares in the company. Our producer was made redundant and the game was nearly axed again. Finally we had to spend a couple of months working very long hours at MicroProse in Chipping Sodbury to get the game finished by the end of March in 1994.

Element 115

Ten years after the game was released, a real element 115 was discovered. Unfortunately, it wasn't named elerium like in the game, but ununpentium.

GeForce problems

GeForce owners have probably encountered display problems that render the game unplayable. This can be fixed though; go to the Windows Control Panel and the DirectX settings. Switch off DirectDraw hardware acceleration and the game should work fine.

Don't forget to switch acceleration back on afterwards, though.


The game is actually Geoscape, the rotating globe and resource management, generating the battlefield conditions for BattleScape, where you conduct tactical combat against the aliens. If you press Ctrl-C (as suggested by the hint "level skip") while in BattleScape, you interrupt the BattleScape program, preventing it from writing the "results" file. Thus you will get the same result as your previous battle. This is a result of the developement history (see the other trivia entries), whereas MicroProse decided that the tactical combat is not enough to be a game in itself, and asked Mythos to write a strategy game around it.


The game is heavy influenced from the TV series UFO . It's about a secret UFO defense base which sends out military aircrafts to shoot down UFOs, sending out squads to seek the wreckage and kill or catch aliens to analyze them.

Multiplayer Workaround

You can actually play "multiplayer" X-COM long before e-mail X-COM... By using sort of a "hack". As the game actually plays through turn by turn on both sides, it is actually possible to take the saved file right at the end of a turn, edit a pointer, and play the "other side" using the engine. And if you exchange files back and forth, you can have a multiplayer game.


A novelization of the game was published through the Proteus imprint of Prima Publishing. It written by Diane Duane and first published in December of 1995.


The last offical patch changed the sound effects of the game. Many people didn't like the new sounds.

V1.4 patch removed the document check copy protection.


A complete version of X-COM is available on Classic Games Collection CD featured with the July 2000 issue of PC Gamer Magazine.
  • There was a "Limited Edition" of UFO: Enemy Unknown for the Amiga CD32 that included a Microprose travel alarm clock.
  • Technology

    X-COM: UFO Defense is one of the few 256-color DOS games to implement dynamic lightning. By using 16 shades of 16 different hues (16 x 16 = 256) as the palette, artists could create isometric tiles whose colors can be gradually changed simply by incrementing each tile's palette entries by 1, 2 and so on. In this way, the same tiles can be shown darker and darker simultaneously on the screen.


    • Amiga Joker
      • Issue 02/1995 – #2 Best Strategical in 1994 (Readers' Vote)
      • Issue 02/1996 – Readers' Special Award for 1995
    • Computer Gaming World
      • May 1995 (Issue #130) – Game of the Year
      • May 1995 (Issue #130) – Strategy Game of the Year
      • July 1996 (Issue #144) – Introduced into the Hall of Fame
      • November 1996 (15th anniversary Issue) - #22 on the "150 Best Games of All Time" list
      • November 1996 (15th anniversary issue) –#1 Top Sleeper Of All Time
      • March 2001 (Issue #200) - #3 Best Game of All Time (Editors' Choice)
      • March 2001 (Issue #200) - #10 Best Game of All Time (Readers' Choice)
    • Electronic Gaming Monthly
      • January 1996 (Issue 78) – Game of the Month (Playstation version)
    • GameSpy
      • 2001 – #35 Top Game of All Time
    • GameStar (Germany)
      • Issue 12/1999 - #73 in the "100 Most Important PC Games of the Nineties" ranking
    • IGN
      • March 2007 - #1 PC Game of All Time
    • PC Gamer
      • April 2000 - #15 on the "All-Time Top 50 Games" poll
      • October 2001 - #3 on the "Top 50 of All Time" list
      • April 2005 - #8 on the "50 Best Games of All Time" list
    • Power Play
      • Issue 02/1995 – Best Genre Mix in 1994

    Information also contributed by Adam Baratz, Andrew Grasmeder, Der.Archivar, Entorphane, Kasey Chang, Lord FlatHead, Heikki Sairanen, Martin Smith, PCGamer77, Pseudo_Intellectual, robotriot, Rola, rstevenson, ZuljinRaynor

    Contributed by IJan (1990) on Dec 04, 1999. [revised by : 4 other people]. -- edit trivia

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