This week's Left 4 Dead 2 mutation introduces a game mode so clever, we're surprised Valve hadn't thought of it yet -- or have they? Yes, players will temporarily be able to re-experience the magic of Survival Versus, in which one team of four survivors lasts as long as it can on a chosen Survival map, and then the next team tries to beat their time. The competing teams go back and forth in this manner until one team fails to surpass the other's lifespan.

It sounds like a pretty hectic addition to an already hectic game type. Give it a try this week only if you think you can handle all the hect ... hecticnicity?