I thought I'd post this because there was a thread about Psi-Ops and such in relation to the US Air Force making them freeware. Well, thanks to the US Air Force, Midway Austin's Area 51 effectively became freeware several years ago, although the rights technically belong to Warner Bros now.
A chap sat down and worked some magic on the game to fix the MP, fix the graphics, fix the crashes, and generally make the game playable on your PC and modern OS.
IMO, it's a pretty decent game that feels like a hybrid of Half Life 2 and Turok. (Some members of the Turok 3 team worked on the game. It's very noticable in the monster designs.) David Duchovny voices the main character, and spends the entire game sounding astoundingly bored. Like, the fate of the world is the least interesting thing that has happened to him.
You can download it the improved version here: