Well, Alien Swarm basically is a game Valve paid a group of modders to make and released it for free. Why can be viewed here. Anyway it's a really good game and it would be awesome to get a XoO game going. The game is highly supported by mobs since the main campaign that it comes with is beatable in about 2 hours. What this means is SDK. I downloaded the SDK but haven't looked at it yet spending to much time actually playing the game. Anyway: Steam Page Install Game My Steam info is to your left! (Thanks again Kyoji)
http://www.xoohq.com/forums/showthread.php?t=17252 http://www.xoohq.com/forums/showthread.php?t=17421
I saw those topics, but one was about game maps and the other was in upcoming games, meaning its not out yet. Which it now is. This one is an attempt to get more people to play.