Crimsonland - Crimsonland.com - a top-down shooter with a touch of RPG: gain XP, choose perks, unlock weapons, and blast your way through aliens, zombies, and lizard men. Coming soon to Steam and PS4!
Xonotic - Xonotic is a free (GPL), fast-paced first-person shooter that works on Windows, OS X and Linux.
Alien Shooter 2: Reloaded - Alien Shooter 2: Reloaded combines the elements of Role-playing, Top-down, Action, and Shooter.
Counter-Strike - Counter-Strike is a PC-exclusive FPS video game developed by Valve Corporation.
Assault Android Cactus - Assault Android Cactus is an Action, Arcade, Top-down Twin Stick Shooter, Co-op, Single and Multiplayer video game developed and published by Witch Beam.
Quake - Quake is a series of first-person shooter video games released by id Software.