Scavenge Mode

Scavenge Mode is a gameplay mode announced for Left 4 Dead 2. Each game consists of the Survivors and the Infected competing against each other to achieve a goal. The Survivors' goal is to find 16 gas cans hidden throughout the map and bring them back to a generator, using the gas as fuel.

The Survivors will have 30 seconds to set up and grab their weapons, while the Infected attempt to find ambush spots. Once the round starts, the Survivors have 2 minutes to find the canisters, with an additional 20 seconds for each canister they find, before the round ends. Overtime is possible, if the time limit runs out and a survivor is holding a gas can, the game will not end. Instead, it will continue until they pour the can into the generator or a infected team member causes them to drop the can. The Infected team's goal, much like any Versus match, is simple: kill the Survivors as fast as you possibly can. When the round is over by any means, teams will switch sides. It is at this point that the new Survivors will have to get at least one more gas can than the previous team in order to win the round. It's recommended that the Survivors watch their aim while shooting at Infected to avoid accidentally setting off the gasoline into a burning inferno. At the same time, this can be used as an advantage for the Infected team, simply because the Spitter has the ability to destroy gas cans with her acidic spit.

For gameplay reasons, gas cans have an aura light around them to help Survivors pin point where gas cans can be located. There are two aura colors, white aura when they are on their original position and yellow aura when they have been dropped by Survivors. White aura gas cans are invulnerable to damage, while yellow gas cans can be shot or spit on and destroyed.

Trivia

 * The videos previewing this mode were the first to show the Special Infected's new in-game appearances.