Link to list of communites
List of places communites to check out.
Links:
FreeDoom - An free version of DOOM for the DOOM engine that rocks.
LibreQuake - Free content first-person shooter game for Quake 1.
Blasphemer - A theme of metal-inspired dark fantasy for Heretic engine.
Freedom Scoops - From the creator of LK, A cereal themed open source game for DOOM engine inspired by Chex Quest.
Xonotic - A fast paced open source arena game based on darkplaces.