Left 4 Dead 2 Linux Beta is Now Available
"The beta build not only allows Linux owners to play the game natively, it is also the testing ground for our new Extended Mutation System," the L4D2 team stated in a blog post. "If you currently own Left 4 Dead 2, You should see 'Left 4 Dead 2 Beta' in your library. If it doesn’t show up, restart Steam. This is a complete build of Left 4 Dead 2, so the build is as large as the current game."
Even though it's intended for Linux, the beta version also contains updated Windows and Mac clients, so you can still test the beta even if you're not running under Linux. The beta includes reworked add-on management to improve stability and a few other changes.
Supported campaigns in the Linux version include Diescraper Redux, Urban Flight, Back to School, and City 17.