Java Gamepad API for multiple platforms
TurboSphere is an easy to learn and powerful JS based game engine.
A multiplatform game engine for interactive fiction experiences
Scriptable frontend for media applications.
An extensible development framework for roleplay games.
Pear3DEngine is a modern and modular 3D development framework
Open Source Virtual World and MMOG Development Platform
CLM for Joomla! 1.5 + 2.5
Powerful html5 & javascript library for creating applications & games.
An HTML web game platform
Cross-platform 2D game engine
Game framework on top of Python, Panda3D and Twisted
Basic real-time simulation engine in C++
Atlarius is no longer under development.