While Turtle Rock Studios may be all done with Evolve and moving on to other things, they still haven't forgotten their original zombie baby, Left 4 Dead. Eight years after the game's initial release, the final campaign was released this past weekend for the PC version.
Titled "Dam It," this campaign is rough around the edges compared to the others and there are some known bugs, but for fans of the title, it should provide a new level to play after all these years. It also helps to bridge a little bit of the narrative arc between the "Dead Air" and "Blood Harvest" campaigns. The new campaign, along with a couple new survival maps, can be acquired from this site.
Even if you're not interested in picking up the new campaign, you should check out the Auger Resources site where you can download it. There's a full map of the campaign along with some notes from the devs and a few pictures of real places/landmarks that they used as inspiration for the level design. It's kind of a cool look into the thought process behind how they came up with this.