"Da Kills" Final Release (8-1-1995) is an old partial mod with single player, co-operative (required to finish), and deathmatch support. Brief description/story: You and your buddies were sent to an UAC WDS -- Union Aerospace Corporation Waste Disposal Site -- to search for any survivors and activate the automatic self-destruct in the center.
Co-operative play! It is for players who want
serious play instead of deathmatches. It includes
a short, interactive story. The only way to find
out the whole story is by playing!