Artifact, Valve's newest game, is due out on November 28th and it will be coming with same-day Linux support. Valve provided me with an early copy and it's pleasing to see it running well.
Since Julian Gollop and Snapshot Games are closing in on the third backer build of Phoenix Point they decided to tease us with a new trailer to show off some new bits.
While I haven't seen it noted in any of the recent changelogs for the Steam Client Beta, it seems it has an updated Steam Runtime in need of some testing.
Egosoft have officially announced their latest space sim X4: Foundations is going to launch on November 30th, although the status of the Linux build isn't fully confirmed.
Gift of Parthax is an arena fighting game where you play as a Wizard who can create their own spells, looks interesting and it now has a Linux beta available for testing.
The RPG title has finally gone forward with its promised Linux support and now has an opt-in beta on Steam. I've had the chance to play a little and have enjoyed what I have seen.