Counter-Strike - Counter-Strike is a PC-exclusive FPS video game developed by Valve Corporation.
Unity - The multiplatform game creation tools for everyone.
Xonotic - Xonotic is a free (GPL), fast-paced first-person shooter that works on Windows, OS X and Linux.
Godot Engine - Feature-packed 2D and 3D open source game engine.
Rage - Rage Software, also Rage Games and FX Digital Network, was a British video game developer.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.