Left 4 Dead 2: The Last Stand, the official version of the community-created update to Valve's multiplayer zombie shooter, is now available.

The Last Stand features a new campaign based on the original survival map, but this time if you can blow up a horde of infected, you can actually escape to safety. There are also 26 new maps in Survival mode, four new arenas in Scavenge mode, two new melee weapons (shovel and pitchfork), and 30 new achievements.

Less obvious improvements include new animations, restoration of unused dialogue, the addition of a generic infected model from the original Left 4 Dead (with gore!) ), new Rocketdude and Tank Run mutations, UI improvements, and "tons of bug and exploit fixes." To read the full patch notes, click here.

To make sure everyone can see the full scope of this major update, "Left 4 Dead 2" is free on Steam until September 27, and if you like it and want to continue your zombie busting shenanigans, you can buy it for 80% off, or just $2 until September 28! The sale is going on now, too.