Godot Engine - Feature-packed 2D and 3D open source game engine.
Unity - The multiplatform game creation tools for everyone.
Struckd - 3D Game Creator - Struckd is the next-generation gaming platform for user created content where people of all ages...
Unreal Engine - Unreal Engine 4 is a suite of integrated tools for game developers to design and build games, simulations, and visualizations.
Reality Factory - Reality Factory is a free suite of game development tools for building 3D games.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.