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. During the game's development Turtle Rock was acquired by the Valve Corporation, the game brought in-house and the Turtle Rock studio closed down. In 2010 Turtle Rock Studios was reestablished as an independent business.

It is unknown how or why Valve Corporation does not possess legal title to the Dam It prototype material and its associated intellectual properties.

For reasons as yet unknown, work on this campaign ceased during its development. Although highly detailed in some parts, many textures are missing or filled with temporary placeholders and the edge of the playable area is often visible. The released version of Dam It contains no campaign-specific lines of character dialog. Code changes were not included in the version released to the public. The ending credits differ visually and player scores are not recorded.