Xonotic - Xonotic is a free (GPL), fast-paced first-person shooter that works on Windows, OS X and Linux.
Miasmata - Miasmata is an Action-Adventure, Horror-Survival, First-person, Open World, and Single-player Simulation created and published IonFx Studios.
Quake - Quake is a series of first-person shooter video games released by id Software.
Darkout - Darkout offers wonderful amalgamation of Action-Adventure and Horror-Survival aesthetics and lets you enjoy unique RPG and Sandbox elements.
Counter-Strike - Counter-Strike is a PC-exclusive FPS video game developed by Valve Corporation.
Don’t Starve: Together - Don’t Starve: Together is the award winning Expansion pack of the popular Don’t Starve that adds Multiplayer functionality to the game.