Pygrid is an open-source and cross-platform pygame/python 2D engine.
A multiplatform game engine for interactive fiction experiences
A world editor for HGE game engine written in python and uses OpenGL.
A 3D, fully concurrent game engine
A cross-platform game framework based on OpenGL and GObject.
A retro style video game engine for RPGs and adventure games.
A game development kit for Sifteo Cubes.
2D Game Engine, based on OpenGL and focused on Isometric Games
3D game engine for C and C++
A graphics engine + toolkit.
A 2D tile map editor created using .NET framework.
A truly extensible cross-platform game engine
3D world editor for game development
A lightweight HTML5 Game Engine
A very small multi-platform game engine for creating desktop games.
Little game background framework in java.