The Challenge is a brand new Early Access adventure game powered by the Unreal Engine where you're tasked with protecting time. It has nice graphics, but boy is it rough.
Streets of Rogue is a new game from Matt Dabrowski that blends beautifully a number of different genres. It has elements from RPGs, action like it's from a top down shooter and so much more.
Day of Infamy is the new FPS from the Insurgency developers New World Interactive. It has a Linux version, even though it's not advertised yet. It seems to work pretty well and they just updated the game.
7 Days to Die is the Kickstarted zombie survival game from The Fun Pimps, colourful history between me and them aside, the game has come a long way. This major update has done a lot for it.
Slime Rancher is the incredibly cute games about catching creatures called slimes, farming and exploring. The new update is out featuring the new crystal slimes.
Shadow Warrior 2 was due to get a Linux version, then suddenly information on it vanished from the Steam page and Humble Store. The plot thickens from there.