Left 4 Dead 2 adds Cold Stream and four original Left 4 Dead campaigns.
Valve has released a massive update for Left 4 Dead 2 today, adding five additional campaigns and access to all of the game's "Mutations." The update is now available through Steam on PC and Mac, but Valve says the same update for the Xbox 360 version will be delayed "a few days."
Valve blames the delay for the Xbox 360 version of the Cold Stream update on the need to "fix a few last [minute] pieces." There is no new release date for the console version.
Today's Left 4 Dead 2 update adds the community-created campaign "Cold Stream" as well as four campaigns from the original Left 4 Dead: "Death Toll," "Dead Air," "Blood Harvest" and "Crash Course." In porting those four campaigns, Valve has made a long list of tweaks to eliminate exploits, which the developer describes in a news update.
Dozens of Mutations that play with the standard rules of Left 4 Dead 2 are now available to play at any time, instead of on a weekly, rotating cycle.
Today's update is free for owners of the PC and Mac versions, which is currently on sale for $4.99 USD. The Xbox 360 update will cost 560 Microsoft Points.