A graphics engine + toolkit.
Sprite Font Creator
Cross platform 2D game creation framework with Python bindings
Open Source Virtual World and MMOG Development Platform
Access to Irrlicht Engine SDK from assembler, C, Python, Basic, Pascal
Game framework on top of Python, Panda3D and Twisted
The Lambda-Engine is a cross platform game engine.
Make games with Lego-like building blocks
Atlarius is no longer under development.