Counter-Strike - Counter-Strike is a PC-exclusive FPS video game developed by Valve Corporation.
Tribes Ascend - Tribes Ascend is an Action and a Free First-person Shooter video game created and published by Hi-Rez Studios.
Xonotic - Xonotic is a free (GPL), fast-paced first-person shooter that works on Windows, OS X and Linux.
Dead Frontier - Dead Frontier is among the few zombie based video games that you can obtain in your web browser and for free.
Rage - Rage Software, also Rage Games and FX Digital Network, was a British video game developer.
Prey 2006 - 2K Games offers a great game named a Prey is an Action-Adventure, First-person Shooter, Single and Multiplayer video game.