Dam It

Dam It is an unfinished campaign for Left 4 Dead that was made by the original creators of Left 4 Dead, Turtle Rock Studios. It was later released on the website, augerresources.com, on November 7th, 2016 and is available for free exclusively on the PC version of Left 4 Dead.

Although it is largely uncompleted, the campaign can be played through in all modes. It consists of only three levels and was intended to bridge the gap between the campaign Dead Air and Blood Harvest.

The campaign was released alongside two standalone Survival maps, Coal Freighter and Highrise.

Official Description
Dam It stitches Dead Air and Blood Harvest together. It’s gray box, and some code features are missing but it’s playable from beginning to end. It also includes two standalone survival maps that never shipped.

Behind the Scenes
Turtle Rock began work on Left 4 Dead in 2005, then was later acquired by the Valve Corporation; after Left 4 Dead the studio was closed down and rights reverted to Valve. Turtle Rock Studios was reconstituted as an independent studio in 2010.

As such, it can be seen in the campaign that it was in its early stages when work on it stopped. Some textures are missing, or replaced with temporary placeholder textures, and the edge of the playable area can often be seen. The credits that roll at the end of the campaign also look different, and are most likely an earlier design.