This page is for the original game. For the reboot, see XCOM: Enemy Unknown.
<path-to-game>\X-Com UFO Defense\XCOM\
The UFO Extender program runs on the Windows version, providing a mouse-resizable window, a smoother-running, more responsive screen than DOSBox, and a host of fixes for various bugs or exploits in the game.. It also supports the use of higher-quality .mp3 music from the PlayStation release, and keyboard shortcuts. XcomUtil provides bug fixes, including for the disjointed-base bug, and additional ease-of-use features like the automatic re-equipping of soldiers before a mission and appending rank and stat info to soldier names.
Both also offer many gameplay modifications such as enhanced weaponry, different starting-base layouts, and randomized terrain and UFO layouts. These are all optional and turned off by default.
The programs are confirmed to run on Windows 7 as well as older operating systems, and with the Steam release.
XcomUtil supports the UFOExtender launcher, but assumes the use of DOS or DOSBox at several points in the installation process, so specific steps are required to run them simultaneously:
Battlescape=X-COM UFO Defense PSX - 10 - Battlescape1.mp3
Start Menu=X-COM UFO Defense PSX - 09 - Final Briefing.mp3
Bad Ending=X-COM UFO Defense PSX - 09 - Final Briefing.mp3
Good Ending=X-COM UFO Defense PSX - 12 - Mission Accomplished.mp3
Geoscape=X-COM UFO Defense PSX - 01 - Geoscape1.mp3
Dogfight=X-COM UFO Defense PSX - 08 - Dogfight.mp3
Mission Debriefing=X-COM UFO Defense PSX - 07 - Debriefing.mp3
UFO Assault=X-COM UFO Defense PSX - 05 - Briefing1.mp3
Base Defense=X-COM UFO Defense PSX - 06 - Briefing2.mp3
Base Attack=X-COM UFO Defense PSX - 05 - Briefing1.mp3
Mars=X-COM UFO Defense PSX - 07 - Debriefing.mp3
Terror Mission=X-COM UFO Defense PSX - 06 - Briefing2.mp3
DOS/32A is a more advanced extender and open source replacement to DOS4GW. It can improve both performance and stability of X-COM.
To improve DOSBox performance make the following changes to the DOSBox configuration file:
cycles=auto limit 10000
UFOPedia has an excellent article on this here.
The original DOS version of the game has a bug which would run the game at the Beginner difficulty regardless of what the player actually selected. This bug went undetected until the Collector's Edition was released. The complaints regarding the game being too easy even at the highest difficulty setting led to the sequel's difficulty being scaled up so much that it's easiest difficulty was harder than the intended hardest difficulty for this game. If using the DOS version, XcomUtil also patches this bug.
Apparently certain 1.4 versions of the game shipped without an updated MT-32 driver causing the game to choke when attempting to load it. Use this patch and place it in the sound\ folder. Overwrite if necessary.