Cold Stream

Cold Stream is the third DLC for Left 4 Dead 2. It was announced in a blog post on February 16, 2011. A beta was released on March 22, 2011 on Steam, and it was officially released on Steam July 24th, 2012. Cold Stream was released on the Xbox Marketplace August 3rd, 2012 for 560MSP.

Cold Stream is unique in that every chapter ends with a gauntlet crescendo event leading to the safe room. Even the finale Cut-throat Creek is a gauntlet panic event through the entire chapter, similar to The Bridge in The Parish.

Only for Left 4 Dead 2

 * Cold Stream, a community-made campaign from the creator of the 2 Evil Eyes community campaign.
 * Ports of Death Toll, Dead Air, Blood Harvest, and Crash Course.
 * Play all Mutations anytime you want.

Achievements

 * See Main Article: Achievements

The Xbox 360 version of the Cold Stream DLC has no unique achievements added to the game.

Beta
Cold Stream was released to the public on the official servers on PC/Mac via beta release on March 22, 2011 for play testing and bug-seeking, such as finding nav-mesh bugs, navigational issues, hit box problems, missing zombie ladders, art problems, and more.

An in-game bug reporter was activated at the same time allowing players to send feedback and bug reports. This feature was announced by Valve to be extended eventually to work with other community campaigns. But strangely, there's no "Report Bug" button in the main menu or the in-game menu, which requires writing "bug" in the Developer Console yourself.

Players can also post feedback on the official forums in the Cold Stream section. Development of Cold Stream can also be followed on Valve's official twitter account located here.