Godot Engine - Feature-packed 2D and 3D open source game engine.
ENIGMA – LateralGM - LateralGM is a powerful IDE for ENIGMA, and both of these combine to offer you a cross-platform game environment.
Unity - The multiplatform game creation tools for everyone.
Unreal Engine - Unreal Engine 4 is a suite of integrated tools for game developers to design and build games, simulations, and visualizations.
Lobster - Lobster is a game programming language.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.