Valve have taken the wraps off of a brand new mode to be included in their upcoming cooperative first-person shooter zombie fest, Left 4 Dead 2, called Scavenge.

In Scavenge mode, players on the Survivor side of the team are tasked with collecting gas canisters to start up a generator located somewhere on the map – every time a member of the Survivors adds another canister to the generator, more time is added to the clock and the team scores a point.

Members of the opposing Infected team, however, must prevent the Survivors from refuelling the generator using any method they can, including attacking Survivors, destroying gas canisters, or simply keeping them occupied until the clock runs out.

Each team gets a chance to play as both Infected or Survivor, the winners being determined by the amount of successfully delivered gas canisters at the end of each round. Sounds an absolute riot!

You can watch a gameplay trailer from Left 4 Dead 2 featuring the new Scavenge mode below:

Left 4 Dead 2 releases November 17th and November 20th in North America and Europe respectively, as well as Australia.