3D game engine/framework in C, with Luajit and Python bindings now
A pure Go game engine
3D Procedural Game Engine Using OpenGL
Orx: Portable Game Engine
Engo is an open-source 2D game engine written in Go
Paintown is a 2d fighting game engine.
Cross platform 2D/3D game engine written in C++11 & OpenGL ES 2/3
Educational framework for OpenGLES, OpenCL and OpenAL
Little game background framework in java.