3D game engine/framework in C, with Luajit and Python bindings now
A modern, cross-platform Quake game engine based on FitzQuake.
DOOM / Heretic / Hexen source port with enhanced graphics and UI
Cross-platform 2D and 3D game engine
3D Game Engine
A basic 3D environment with a first-person POV
3D game engine for C and C++
A complete 2D Game Engine with built in drag and drop editor
A DirectX based graphics/physics engine