Free, cross-platform 2D game engine powered by Haxe and OpenFL
3D game engine/framework in C, with Luajit and Python bindings now
Open game and rendering engine packed into a JavaScript framework
Python MUD/MUX/MUSH/MU* development system
Open source library for creative expression on the web, desktop, etc.
A completely free, open-source, 2D game engine
JavaScript-based game engine designed to empower developers
Javascript library for making tile based games
Turbulenz is a modular 3D and 2D game framework
Educational framework for OpenGLES, OpenCL and OpenAL