Valve has announced via the Left 4 Dead blog the Cold Stream DLC, which consists of the Cold Stream, Blood Harvest, Crash Course, Dead Air, Death Toll and No Mercy maps will be released on Mac, PC and Xbox 360 July 24.
Valve said there are some “surprises and details,” in store later, but for now it “just wanted to confirm an often requested feature.”
“With the update going out at the same time, all of the mutations will be available at all times,” said the blog post. “This will allow players to choose to match into games playing Taannkk!, Gib Fest, or even a user created mutation like Confogl.”
More information will be available closer to launch.