X-Men: The Ravages of Apocalypse

X-Men: The Ravages of Apocalypse is a third-party total conversion released for Quake in 1997. In the game, the mutant Apocalypse is taking advantage of the aftermath of the Onslaught incident, having captured the X-Men and making an army of clones in his quest for domination.

The game was originally released commercially, but was re-released as freeware in 2006. Running the game requires either a copy of Quake, or an asset replacement pack.