http://forum.grangerhub.com/ - GrangerHub is a player community site for the FPS/strategy game Tremulous, which features ultra fast game play, wall crawling aliens versus humans locked in deadly combat from strategically built bases. The game is free open source software (FOSS) under GPL2 license.
If you've never heard of it: The game started as a total-conversion of id Software's Quake III, then went stand-alone when the Q3 engine was open sourced, switching to the ioquake3 engine (their forums also running discourse!).
We're overhauling the game and we're releasing a 10-year anniversary update (S00N ). Our forum is used for development, also for clans, custom maps and mods, and more.
We wanted to get away from the environment and forum system (smf) of the "official" tremulous.net site, and liked the ideas presented in the "Universal Guide to Civilized Discourse" and the discourse FAQ. This inspired us to create our own Code of Conduct guide for our site staff and mods. Check us out!