- Executive Meddling: It's more or less an open secret that Interceptor and (definitely) 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 focus away from their own core works.
- Franchise Killer: 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: Terror from the Deep, Interceptor and Enforcer were mostly the brainchildren of MicroProse executives, rather than the core X-COM team, who wanted to make Alliance and Genesis, but were forced to make the (universally-agreed) sub-par games to placate their overlords.
- 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 the friendly aliens to survive against hostile aliens. An unfinished build of the game was discovered in late 2011.
- X-COM Genesis, returning to the gameplay of UFO Defense.
- Dreamland Chronicles, Julian 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.
- Wiki Rule: UFOpaedia, and the Wikia XCOM Wiki.
Trivia / X-COM