X-COM: UFO Defense

X-COM: UFO Defense

X-COM: UFO Defense is a genre-defining strategy game released in 1994 combining both strategic and tactical gameplay.


The Geoscape.
The Geoscape.

Originally released in the UK as UFO: Enemy Unknown; X-COM: UFO Defense combines challenging turn-based gameplay with base building, research management, and persistent squad members.

The game was originally released in 1994 for PC, Amiga, and Amiga CD32. It was also later released for the PlayStation. X-COM: UFO Defense, along with four other X-COM games, were released digitally via Steam on September 4, 2008.

Throughout the game, players will encounter a multitude of alien races that are intent on subjugating the people of Earth. The Extraterrestrial Combat Unit must prevent this from happening by tracking and shooting down UFOs, stopping terror attacks on major cities, and eliminating alien bases before they can infiltrate governments across the world.

Bases, workers and squad destinations are managed in the Geoscape view, before switching to the battlescape view for missions.

Troops sent on missions improve with the actions they take and can individually be equipped with a variety of firearms and grenades. Upon elimination of all the aliens on the battlescape, alien artifacts will be returned to the base, where players can assign scientists to start researching different weapons and technology. New weapons, gadgets, and aircrafts can be manufactured by engineers, adding items like medpacks, hover tanks, and plasma weapons to the arsenal.


UFO: Enemy Unknown was originally conceived as a sequel to Laser Squad, another game by Julian Gollop.


Troops leave their Skyranger to investigate a small UFO.
Troops leave their Skyranger to investigate a small UFO.

Shooting down UFOs will allow a transport ship to land at the crash site, where troops will be tasked with eliminating any surviving aliens. All missions play out in turns, with the player always going first. Troops have Action Points that are depleted by everything from moving and shooting to turning and priming grenades.

Alien weaponry is far superior to the the troops' ballistic rifles and heavy cannons, requiring caution to keep squad members alive. Reaction fire allows soldiers to save action points for the alien turn, and, depending on an individual's reaction stat, he or she may fire on an alien that moves into line of sight. UFOs may also land; players can take advantage of this by sending transport ships to catch the aliens off guard. Research rewards are often better, as the UFO itself is not damaged, unlike when alien crafts are shot down. However, this also means that there will be more aliens to contend with on the ground.

Terror missions are arguably the most difficult, as they occur at inopportune times around the world and last only a few in game days, leaving little time to prepare before the city is ransacked. Failing or ignoring these missions will make the local government unhappy, which might lead to funding cuts at the end of the month. In terror missions, the aliens set out to kill as many civilians as possible, so players must attempt to protect citizens by quelling the alien threat as quickly as possible.

Aliens also will try to construct bases on Earth, as evidenced by heavy UFO activity in certain countries (a month by month stat page can help highlight this information). These missions are completed by killing or capturing all aliens inside. It is worth noting that at the core of the bases, a high-ranking alien can usually be found who will yield valuable information if taken alive and interrogated.

The world map progresses with time, and missions can be taken during night or day. All the aliens have the unique advantage of seeing as well at night as day. Therefore players can opt to wait until daylight to attempt a given mission, in order to not be at a disadvantage.


A sectoid.
A sectoid.

There are five alien races, each with an associated support unit, usually only seen on the terror missions or within their bases.


The Sectoids are based on the greys. They pair with Cyberdiscs - mini UFOs that hover and shoot, but explode when destroyed.


The aptly named Snakemen are physically tough units that team up with the terrifying Chryssalids, fast moving bipedal insects that turn their victims into zombies, which can then turn into more Chryssalids.


Floaters have no legs, and instead float around and guide their giant accomplices, the Reapers.


Purple and green Mutons, who couple with Celatids - purple floating creatures that shoot acid. They're also accompanied by Silacoids, which are essentially big moving rocks.


The orange robed Ethereals have the strongest psychic powers, and have a mechanized form of the Reaper for their terror missions called Sectopods.

Base Building

The Base management screen.
The Base management screen.

Construction of multiple bases is critical to later success, though funding and management of multiple bases provides it's own challenge. Players must hire and pay all personnel and also pay upkeep for various facilities on a monthly basis. Radar systems, storage areas, living quarters, research, and manufacturing areas may also be constructed. Later, base defenses, alien containment, and more hangar space become important to the mission. Management of weapons and ammunition for troops and ships also occur here.

Should an X-COM base be invaded by hostile forces, the base will need to be defended by the player's forces within that base. Aliens will infiltrate through possible entry zones, like gun ports and hangars. Supplies that aren't allocated to soldiers will be in storage areas. Not all of the base is well-lit, particularly hangars, making visibility a problem. Creating defensive structures and bottlenecks around entry points are ways to minimise the damage taken during base defence scenarios. If players fail one of these missions, the base will be lost.

Research & Development

'Laser Defences' in the UFOpedia.
'Laser Defences' in the UFOpedia.

Hiring and utilizing scientists and engineers allows progress in the game, both technologically and story-wise. More powerful and varied weapons are made available, as well as personal armor, building types, and information about the aliens. Psychic research also becomes part of the gameplay, allowing the player's troops to use the alien's mind control abilities against them. The later aircraft are necessary for completing the game, and only by bringing in live aliens will scientists discover a way to eradicate the alien menace. Learning about the aliens opens up new avenues of research, propelling players toward having the tools to bring about the game's conclusion - as long as enough scientists are allocated to the task.

UFO Interception

When pursuing enemy craft with an aircraft on the Geoscape, players may get within firing range. This spawns an interceptor minigame, which pits the player's craft against a UFO. Smaller UFOs tend to be more fragile and less heavily armed, while the top-of-the-line enemy ships can easily destroy more basic X-COM crafts - especially if the aircraft's armament doesn't have sufficient range. When at a stand-off distance, players can minimize the pursuit window to manage other on-screen events (like other pursuit craft).

On the interception screen, the green-colored field on the far left of the pop-up visualizes the player's distance to the enemy, and the range and ammunition that the player's weapons have. The four upper-right buttons are the approach tactics (clockwise from upper left):

The interception screen.
The interception screen.
  • Standoff - maintain maximum distance but continue pursuit
  • Long distance attack - fires at a low rate of fire and at maximum possible distance
  • Moderate attack - fires all weapons at minimum necessary distance
  • Point blank - charge right at the enemy vehicle, weapons blazing. This increases damage potential but puts the interceptor at greater risk

The silhouette of the X-COM craft shows the percentage of damage that the craft has taken, this is indicated by glowing red, starting from the tip and working its way to the back.

The final two buttons are retreat, and visualize enemy. The former simply disengages from combat, which flies back to base. The latter shows players what the enemy craft looks like.

Finally, there is a numerical distance rating that corresponds to the representation on the left.

Should the player's craft be able to land and deploy troops, and players force the enemy to crash-land or it lands on its own, players will instantly land and begin a ground mission. It's also possible that the enemy could run away, destroy the X-COM craft, cause the player to retreat, be completely destroyed, or crash into the sea.

PC Requirements

  • Supported OS: MS-DOS 5.0/Windows 95
  • Processor: 80386 processor or better
  • Memory: 4Mb RAM
  • Sound Cards Supported: AdLib compatible cards, SoundBlaster compatible cards and the Roland LAPC