Survival Mode

Survival Mode is a new mode comming with the DLC survival mode pack. The game throws zombies at you until you die. You cannot win, instead attempt to set records for your longest time survived. There mode will be available for 12 maps when it is released.

Each survival match starts with a setup time, as you can scour the map for weapons and equipment, like health kits and gasoline tanks. You can take as much time as you want, as the timer at the top of the screen doesn't begin until someone hits the button that starts the zombie horde. Once the button is pressed, the action gets off to a furious start and escalates from there. 

You'll have to move from room to room to get more items and ammo, meaning you'll have to think on your feet. You'll also be busy keeping your team mates alive as you try to survive for as long as possible. Don't expect the game to go easy on you, either. In one battle, there was the tank, a boomer, a couple of smokers, and a hunter hitting at the same time. It has been told by Valve that it's even possible to get two tanks at the same time.