F.E.A.R. Combat is a multiplayer FPS from Monolith and Sierra. It is a repackaged version of the competitive multiplayer modes of F.E.A.R., and is downloadable and playable for free. It features 22 maps, 10 game modes, support for user-created content, and the ability to play against owners of the original game as well as other F.E.A.R. Combat players.
You can acquire a game key and download the game here:
http://www.joinfear.com/main