Left 4 Dead 2, it's been announced, will feature a brand new Survivors vs. Infected mode called Scavenge where the four human Survivors must seek out gas cans and refuel a generator before time runs out; the Special Infected will hinder progress by directly harming the Survivors, destroying gas cans to prevent time extensions, or simply letting the clock run out.  At the end of the match, players switch sides and the round begins anew.

Survivors will have an expanded arsenal that includes incendiary and explosive rounds and brand-new melee weapons such as baseball bats, frying pans, and chainsaws.  Players on the Infected side can use the old standbys (Tank, Boomer, Smoker, Hunter) and the three new Special Infected: Spitters (who spew a corrosive bile that is harmful to the touch), Chargers (a quick-moving Infected with an oversized arm to throw Survivors around or pulverize them against the ground), and Jockeys (acting as the proverbial monkey-on-your-back, they will latch onto a Survivor and lead them to traps or groups of Infected).

The game will also feature an updated AI Director that change weather effects, objects, and pathways to further randomize each and every session through the game's maps.

Left 4 Dead 2 ships November 17th for the Xbox 360 and PC.