Left 4 Dead 2′s Cold Stream DLC has been through more tests than a guinea pig that just survived a nuclear blast. As well as the new map, the DLC contains Blood Harvest, Crash Course, Dead Air and Death Toll from the first game, but that’s not new news. The fresh meat on this data morsel is the availability of all mutations at all times and Valve promise “other surprises and details” soon. July 24th is the release date. That’s the release date for the DLC, by the way, not the guinea pig. The guinea pig is too uncanny to release into the wild so top scientists have sealed it in a lead box which is currently being dropped into a furnace.