Space Station 13 is a paranoia-laden roleplaying game set against the backdrop of a nonsensical, metal death trap masquerading as a space station.
Read more here.
Main website for the /tg/station13 community is http://tgstation13.org
Forum is run at http://tgstation13.org/phpBB/
General IRC channel for anything /tg/station13 related is #tgstation13 on irc.rizon.net
IRC channel for the development of code is #coderbus on irc.rizon.net
NTstation's IRC channel for development of code is #nanobus on irc.rizon.net
There are currently three /tg/station13 servers, all hosted by ScaredOfShadows. Sybil and Basil operate coderbus's standard /tg/station13 code while Artyom operates a new branch of code called NTstation.
Download BYOND to play.
Check out these alternative maps that come packaged by default in the game.