Valve has released the first weekly mutation for The Passing DLC for its co-operative zombie shooter, Left 4 Dead 2.

The Passing DLC was released last month and introduced new single player, multiplayer and co-operative gameplay to the game. It also introduced a series of weekly game mode events dubbed “Mutations.”

Bleed Out is a mutation for Campaign mode and gives player temporary health that slowly deteriorates. Players will only be able to boost their health with pills and adrenaline as health packs have been removed from the mode.

The developer will be releasing over 20 mutations on a weekly basis, with the next mutation being called Follow the Liter.

If you haven’t yet downloaded The Passing DLC, you can grab it from Xbox Live for 560 MS Points. You can also browse through our previous coverage or read our review of Left 4 Dead 2 to find out more about the game.