libtwo - All-purpose c++ app prototyping library, focused towards live graphical apps and games
Godot Engine - Feature-packed 2D and 3D open source game engine.
Grit Game Engine - The Grit Game Engine is an MIT-Licensed Open Source Game Engine that is highly scriptable via Lua.
DragonRuby Game Toolkit - DragonRuby Game Toolkit is a commercial-grade, yet beginner-friendly, 2D game engine.
MOS - Lightweight game engine.
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!