Related Work - gamekit-developers/gamekit GitHub Wiki

Related affordable game engine technology

Here are a few links to other affordable game engines, where the source code is available, for less then a few hunderd US dollars.

A more exhaustive listing of 3D game engines (or just graphics engines) can be found here: http://www.devmaster.net/engines/

Maratis 3D http://maratis3d.com, zlib/png license
Hieroglyph3 http://hieroglyph3.codeplex.com, MIT license, DX11 renderer with deferred rendering
Panda3D http://www.panda3d.org, BSD license, browser plugin framework and iPhone
Tubras and irrb Blender exporter, http://code.google.com/p/tubras/
Lightfeather 3D Engine: http://lightfeather.de, zlib license
IndieZen http://www.indiezen.org, zlib license, using BOOST
R5, http://code.google.com/p/r5ge/source/list (Apache)
G3D Engine, http://g3d.sourceforge.net/index.html (licensed under the BSD license)
Sauerbraten / Cube 2, http://sauerbraten.org (Zlib license)
libgdx, Android/PC framework, http://code.google.com/p/libgdx (Apache 2.0 license)
Galaxy Engine, Max, iPhone, iPad, Cocoa, http://code.google.com/p/galaxyengine (BSD license)
Proton SDK, http://protonsdk.com (BSD license witt advertising/attribution clause)
Torque 3D, https://github.com/GarageGames/Torque3D (MIT license)
Urho3d, https://code.google.com/p/urho3d (MIT license)