Godot Engine - Feature-packed 2D and 3D open source game engine.
Unity - The multiplatform game creation tools for everyone.
MonoGame - MonoGame is an open source implementation of the Microsoft XNA 4 Framework.
RPG Maker - Make your own PC game with RPG Maker. Our easy to use tools are simple enough for a child, and powerful enough for a developer. Try it free today!
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
Blacksmith 2D - Black is a highly optimized 2D framework for web, mobile games, and playable ads.