While announcing that it is working on last minute changes on the maps, Valve declared their intention to involve community members to any find bugs in their maps. The deal is that if 20,000 people can survive a campaign from the Cold Stream pack before the deadline, Valve would reward gamers by releasing Dead Air earlier than the rest of the DLC.
The normal process of making the maps bug free involves the company’s own employees testing them on a daily basis. But since the Cold Stream DLC is developed with the community, Valve has given that responsibility to gamers. So, if 20,000 gamers can earn the Stream Crosser achievement before the end of July 10, the developers would as a reward release Dead Air on July 22.
Gamers who don’t possess a copy of Left 4 Dead 2 can buy its PC version on Steam for a 75 percent discount which is valid only till today.