Valve has just announced its plans to release a fan-made campaign by Matthew Lourdelet called "Cold Stream" to "Left 4 Dead 2." Unlike the official campaigns, "Cold Stream" will not have any new audio or cinematics due to obvious modding constraints so it will be used as an experiment to see if the player audience enjoys playing a map that's purely about gameplay.
Valve has also announced that it plans to import the three remaining campaigns from L4D1, so players of "Left 4 Dead 2" will have the full game to enjoy.
The campaign will be released on all platforms for free shortly after the release of Portal 2.
