a short-lived beta run, Valve has deemed Left 4 Dead 2 on Linux to be complete. The Linux version and the Extended Mutation System now join the full release of Left 4 Dead 2 on Steam.
Left 4 Dead 2, which first launched in late 2009, hasn't slowed down these past four years. The Steam version has received numerous updates, DLC add-ons and even Steam Workshop support. As of last September, the Left 4 Dead series had eclipsed 12 million sales.