OgreWin3D
Vivid3D is a C++ IDE/3D engine, with python scripting.
Lego Island 2 Game Editor
IRB is a game creation toolkit
evolution for vegastrike SpaceSim/Combat/Trade game
Animation graph editor.
3D Game engine
Multi-threaded 2D Renderer licensed under the Mozilla Public License
Phobos editor is a generic resource editing system.
Pear3DEngine is a modern and modular 3D development framework
cross-platform 2d game engine
Map and logic editor