- Franchise Killer: X-COM: Apocalypse. MicroProse later produced X-COM Interceptor, a space strategy and sim hybrid, but it was generally panned by critics. They ditched the retro-style art, and replaced it with even worse art.
- God Does Not Own This World: X-COM: Terror from the Deep, Interceptor and Enforcer were primarily the handiwork of MicroProse executives, rather than the core X-COM team who wanted to pursue Alliance and Genesis instead (see below). But were forced to develop these sub-par games to placate their overlords.
- Referenced by...: NASA named one of their projects after XCOM (theirs is X-Ray Communications, not eXtraterrestrial Combat). They even use a branch-appropriate green patch with the motto "Communico Confido◊."
- Screwed by the Network: It was an open secret that Interceptor and (especially) Enforcer were self-sabotage on Hasbro's part, having bought up MicroProse simply to eliminate competition and intentionally running the acquired IP into the ground rather than shift resources away from Hasbro's core works.
- What Could Have Been: A few cancelled games.
- X-COM Alliance, a squad-based FPS where a team of X-COM soldiers got teleported away to another world, where they have to work together with friendly aliens to survive against hostile ones. An unfinished build of the game was discovered in late 2011.
- X-COM Genesis would have reverted to the gameplay of UFO Defense.
- Dreamland Chronicles, Gollop's Spiritual Successor to X-COM which, according to Word of God, would have similar gameplay to Valkyria Chronicles.
- The original vision for The Bureau. See its Trivia page for details.
- Wiki Rule: UFOpaedia, and the Wikia XCOM Wiki.
Trivia / X-COM