[Killing Floor](http://store.steampowered.com/agecheck/app/1250/) is a cooperative survival horror first-person shooter on Windows, Mac, and Linux. Slaughter wave after wave of increasingly brutal experimental specimens with 7 different classes to choose from. Notoriously difficult and notoriously fun!
Reddit community and official fansite for the free-to-play third-person co-op action shooter, *Warframe*. The game is currently in open beta on PC, PlayStation 4, Xbox One, and Nintendo Switch. For the new Reddit design, go to https://rwarframe.github.io/#flair to set user flair and text.
Deep Rock Galactic is a 1-4 player co-op-first sci-fi FPS featuring badass space Dwarves, 100% destructible environments, procedurally-generated caves, and endless hordes of alien monsters. Available in Early Access on Steam and in Game Preview on Xbox One and Windows 10 store as an Xbox Play Anywhere Title