Cocos2d for iOS and OS X, built using Objective-C
Rich HTML UI engine for UE4
Wolfenstein 3D HTML5 TOTAL Conversion
3D .NET engine for Windows, Linux, Mac
A game engine written in the D programming language
Python 1.0 - 3.4 bytecode decompiler
a very lightweight advanced terrain-rendering and 3D map rendering sys
A C++ 3D game engine.
A pygame music lib.
Simple workflow engine written in Python to manage program executions.
Plugin based multi-purpose dev tool.
Free-roaming 3D racing game featuring advanced terrain rendering
Editor of virtual worlds.
Cross-platform C framework very compact libraries and tools.
vim-snipmate default snippets
Performance enhancement API for RPG Maker XP, VX, VXA.
Pygrid is an open-source and cross-platform pygame/python 2D engine.