Unity - The multiplatform game creation tools for everyone.
Call of Duty - Call of Duty is a first-person and third-person shooter series by Infinity Ward.
Godot Engine - Feature-packed 2D and 3D open source game engine.
Unreal Tournament - Unreal is a series of first-person shooter video games developed by Epic Games.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
Xonotic - Xonotic is a free (GPL), fast-paced first-person shooter that works on Windows, OS X and Linux.