RetroArch is a frontend for emulators, game engines and media players.
Cerberus Content Management System
OviOS Linux
Game engine supporting many 3D/2D formats and graphic effects
JavaScript framework to build game engines, games, emulators and apps
2D Game Engine
Cross Platform GUI Toolkit
A cross-platform interpreter for many point-and-click adventure games
Android, DOS, FirefoxOS, Linux, MacOS and Windows all in one..
PSP Debug Bash and Multi-Environment Shell
Pye - Javascript Engine For Drawing Fast, Fluid and Dynamic Pie Charts
Very Powerfull Crossplatform Qt Based Music Note Editor[Still Planing]