This was my first tactical game I ever played back in the day, it worked on my old PC a 486, I played all the versions available.
- X-COM: UFO Defense (1993) (also known as UFO: Enemy Unknown and X-Com Enemy Unknown)
- X-COM: Terror from the Deep (1995)
- X-COM: Apocalypse (1997)
I will write up some rules soon.
The premise for the series is fairly simple and straightforward, with variations among them: armies of hostile aliens have begun invading the Earth, killing and enslaving the human race. The mise en scène and trappings of the game closely mirror those of the classic ITV television series UFO. Despite the clichéd setup, the implementation is serious and carefully detailed to give an "authentic" impression.
In all the games, the player is put in command of X-COM (Extraterrestrial Combat Unit), the international military organization set up in the near-future of 1999. By defending X-COM's funding countries (initially Australia, Brazil, Canada, China, Egypt, France, Germany, India, Italy, JapanNigeria, Russia, Spain, UK, USA) from enemy invasion, the force gains monetary support. Any nation may quit, if X-COM's service is deemed unsatisfactory or the nation's government has been infiltrated by the invaders. Through scientific research of recovered alien artifacts, X-COM is able to develop better and more powerful weapons, armor and vehicles to combat the alien menace, and eventually uncover their true nature.
The game takes place within two main views: the Geoscape and the Battlescape, a dichotomy that is the hallmark of the entire series. The Geoscape consists of a global view of the earth from space. The player can view the X-COM bases (in various locations on Earth), make changes to them, equip X-COM aircraft, order supplies and personnel, direct research efforts, schedule manufacturing of advanced equipment, and sell alien artifacts to raise money. From this view the player also directs interceptor and troop transport aircraft on their missions. The Geoscape is continual and not turn-based.
Gameplay switches to the isometric combat view of the Battlescape whenever X-COM personnel come in contact with alien units. This can result from investigating downed enemy space ships, combating alien terrorist activities, or attacking alien bases discovered during play; aliens may also manage to attack and infiltrate one of the X-COM bases. In the Battlescape view, X-COM combatants are pitted against the alien enemies. In addition to personnel, the player may have vehicles such as HWP unmanned ground vehicles outfitted with powerful weapons and heavy armor, but not gaining experience points in battles. Instead of experience points, the combatants gain points in skills like PSI or Morale (random amount depending on how much of the action they did). This mode is turn-based and each combatant has a number of "time units" which can be expended each turn. When all alien forces have been neutralized, the mission is scored based on number of X-COM units killed, civilians saved or killed, aliens killed or captured, and the number and quality of alien artifacts obtained.