What we didn't know at the time was that Valve decided to hire the members of the Alien Swarm team two years ago. Since then the team members have worked on Valve's games like the Left 4 Dead series and the upcoming Portal 2. However the team never forgot about Alien Swarm and continued to work on the game in between their official Valve duties. Today Valve announced that the game will finally be released on Monday as a free download. In addition the game's source code will also be released for free.
Alien Swarm will feature co-op gameplay with up to four players, four player classes and eight unique characters. There will also be 40 weapons and items to use and a title based map generation tool. It will also support Steamworks features like achievements, matchmaking, Steam Cloud save game storage and more.
Gallery: Alien Swarm Screenshots