UFO: Enemy Unknown
UFO: Enemy Unknown, also known as X-COM: UFO Defense and X-COM: Enemy Unknown, was the first game in the XCOM franchise. It was released for the PC in 1993-1994 and later ported to the Amiga and Sony PlayStation.
It was a turn-based combat game with the player taking the role of the leader of an elite paramilitary organization created by a coalition of nations to fight an alien invasion and codenamed "X-COM", short for Extraterrestrial Combat Unit. It was set in 1999 (at the time, still the near future).
The game was followed by X-COM: Terror from the Deep.