Killzone: Shadow Fall - Killzone: Shadow Fall is offering thrilling gameplay, in which you, as the protagonist, need to complete a variety of challenging missions.
Xonotic - Xonotic is a free (GPL), fast-paced first-person shooter that works on Windows, OS X and Linux.
Arma - Experience true combat gameplay in a massive military sandbox.
Counter-Strike - Counter-Strike is a PC-exclusive FPS video game developed by Valve Corporation.
BioShock Infinite - BioShock Infinite is an Engaging, Action-Adventure, FPS (First-person Shooting), Fantasy, Exploration, and Single-player video game created by Irrational Games and published by 2k Games.
Quake - Quake is a series of first-person shooter video games released by id Software.