DLC over here! Valve has announced that, next Tuesday, fans of Left 4 Dead will get a new campaign to play. "Crash Course" will take place between the events of "No Mercy" and "Death Toll," providing a series of survival maps and a streamlined version of Versus mode on top of the new co-op campaign action. The DLC will be free for PC on September 29 ... and 560 ($7) for the Xbox 360 version. Did you hear: a true sequel will be out just 7 weeks later?