Players of Valve Software's zombie slaughtering action game Left 4 Dead can finally download and play the new DLC called Survival Pack on PC and Xbox 360. Apart from several fixes and improvements to the game itself, the pack offers the new Survival Mode. Casting players into the crushing blows of wave after wave of hordes, tanks and specials in Survival Mode, they'll also experience 16 maps including Last Stand -- called the hardest map yet for the game.

Best of all, the Survival Pack is free for everyone. You might want to set your alarm before playing since you're not going to sleep tonight.

Left 4 Dead

    Left 4 Dead is a first-person co-operative shooter in which you play as one of up to four people (called "Survivors"), luckily immune to the virus that's sending most of the population mad, pitched against an endless horde of infected. (Screenshot 1 of 4)

    Left 4 Dead is a first-person co-operative shooter in which you play as one of up to four people (called "Survivors"), luckily immune to the virus that's sending most of the population mad, pitched against an endless horde of infected. (Screenshot 2 of 4)

    Left 4 Dead is a first-person co-operative shooter in which you play as one of up to four people (called "Survivors"), luckily immune to the virus that's sending most of the population mad, pitched against an endless horde of infected. (Screenshot 3 of 4)

    Left 4 Dead is a first-person co-operative shooter in which you play as one of up to four people (called "Survivors"), luckily immune to the virus that's sending most of the population mad, pitched against an endless horde of infected. (Screenshot 4 of 4)