Developer: Grey Matter Interactive
Release Date: November 19, 2001
Source Code Release Date: August 12, 2010
Return to Castle Wolfenstein is a fantastic single player game with lots of little touches you might have missed the first time around and that you don't see much anymore. Still abolutely worth firing up just to blast some Nazis. This source port also includes the multiplayer as a separate app, which still works on the servers running to this day.