Open Game Development

UFO: Alien Invasion (http://ufoai.ninex.info/)

Forum
SourceForge Page
Alien Invasion Wiki

Armagetron (http://armagetronad.net/)

Forum

Armagetron Wiki

Free Orion (http://www.freeorion.org/index.php/Main_Page

FreeCiv (http://freeciv.wikia.com/wiki/Main_Page)

jRisk (http://risk.sourceforge.net/) and TEG (http://teg.sourceforge.net/)

vbGore (http://www.vbgore.com/)