This is probably does not belong on this forum, but this game company has released some game data and it might be interesting for opensource developers to look at.
http://www.threerings.net/code/
See also this guys post somewhere on the internet:
http://forum.freegamedev.net/viewtopic.php?f=3&t=1360
It's not new, but I just happen to be playing that game and I was visiting this forum anyway.
/edit Oh and the major strenght is the portability. The java engine can be loaded from a browser window.
Open source java based engine from Three rings
Moderator: Moderator