Arma 2: Operation Arrowhead - Arma 2: Operation Arrowhead is a Tactical, First-person Shooter, Single and Multiplayer video game created by Bohemia Interactive Studios and published by 505 Games.
Xonotic - Xonotic is a free (GPL), fast-paced first-person shooter that works on Windows, OS X and Linux.
Hawken - Hawken is an Action, Free-to-play, FPS, Robots, Science-fiction, Tactical, Futuristic, MMO, Co-Op and Multiplayer video game created and published by Reloaded Games.
Quake - Quake is a series of first-person shooter video games released by id Software.
Perfect Dark - Perfect Dark is an Awesome, Action-Adventure, Stealth, FPS (First-person Shooter), Single and Multiplayer video game developed by Rare and published by Nintendo.
Counter-Strike - Counter-Strike is a PC-exclusive FPS video game developed by Valve Corporation.