Xonotic - Xonotic is a free (GPL), fast-paced first-person shooter that works on Windows, OS X and Linux.
Turok - Turok is an Action-Adventure, FPS, Survival, Single and Multiplayer video game developed by Propaganda Games published by Disney Interactive Studios.
Unreal Tournament - Unreal is a series of first-person shooter video games developed by Epic Games.
Far Cry - Far Cry is an amazing, Action, First-person Shooter (FPS), Single and Multiplayer video game developed by Crytek and published by Ubisoft.
Quake - Quake is a series of first-person shooter video games released by id Software.
Psi-Ops: The Mindgate Conspiracy - Psi-Ops: The Mindgate Conspiracy is an Action-Adventure, Sci-Fi, Third-person Shooter, Single and Online-Multiplayer video game published by Capcom.