Does anyone here like Half-Life? It was released on the PC in 1998 and then the PS2 in 2001. Half-Life: Opposing Force was released in 1999 for the PC and then Half-Life: Blue Shift in 2001. There's Half-Life 2 and recently Black Mesa was released. Black Mesa is a free download. It's basically the original Half-Life but much more detailed. It's got much better graphics and it's more realistic.
Here are some links to Wikipedia about the various games.
Black Mesa: http://en.wikipedia.org/wiki/Black_Mesa_(video_game)