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 Yogstation community is https://yogstation.net
Download BYOND to play.
Yogstation: <byond server=game.yogstation.net port=4133>byond://game.yogstation.net:4133</byond>
Check out these alternative maps that come packaged by default in the game.