Nova Drift takes a classic arcade-like space shooter, adds in touch of action-RPG elements with upgrades along with a sprinkle of random generation to make something that looks damn fun!
Originally developed for the 41st Ludum Dare Game Jam, ACardShooter is being expanded for a full release and it's due this Summer. Certainly sounds like an interesting idea too.
Releasing this Summer in Early Access, UnderMine looks like a seriously good action-adventure roguelike that will have you dig deeper and deeper for gold and powerful relics.
Zap Blastum: Galactic Tactics looks quite unique, a top-down shooter where you hop from one bit of cover to another with simple controls and they claim it's "The cover shooter anyone can play!".
Pillars of Eternity II: Deadfire from Obsidian Entertainment and Versus Evil should now be considered finished, with a brand new patch available to send it off in style.
With a theme inspired by 80s and 90s action movies, as well as comic book series like Preacher and Constantine, The Unholy Society looks like an adventure not to be missed.
Chronicon might not be a familiar name to some, it's not exactly hugely popular but it does have some of the best action-RPG gameplay available on Linux.
Lost in Sky: Violent Seed is one I've been following for a while and it's really looking good now, it's also on track to release soon with Linux support.