RetroArch is a frontend for emulators, game engines and media players.
A game engine powered by python and panda3d
A tool for converting Xbox 360 shaders to HLSL
A dead simple 2D game engine for Go
Game engine supporting many 3D/2D formats and graphic effects
A cross platform Lua based game engine
Source code of the chapters of the book 3D Game Development with LWJGL
Game engine supporting many 3D/2D formats and graphic effects