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.
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!
Adventure Game Studio - Adventure Game Studio provides the tools to make your own adventure, for free!
Blacksmith 2D - Black is a highly optimized 2D framework for web, mobile games, and playable ads.