OurWorld - OurWorld is an Action, Great Online Virtual World, Social Interaction, MMO, and RPG Simulation by Flow Play.
Xonotic - Xonotic is a free (GPL), fast-paced first-person shooter that works on Windows, OS X and Linux.
YoWorld (Yoville) - YoWorld or formerly known as Yoville, is an Action, Browser-based, MMO, RPG, Single-player and Multiplayer, Social networking, and Virtual World Simulation developed by Big Viking Games.
Counter-Strike - Counter-Strike is a PC-exclusive FPS video game developed by Valve Corporation.
Movie Star Planet - Movie Star Planet is an Online Virtual World, MMO, and RPG Simulation by MovieStarPlanet.
Quake - Quake is a series of first-person shooter video games released by id Software.