Make Sail is a game currently in development that's inspired by the sailing adventures of Wind Waker and the creativity and construction from Kerbal Space Program and it seems it will come to Linux.
Darkest Dungeon is about to get darker with a new DLC 'Darkest Dungeon: The Color of Madness' involving an alien shard that's crashed into old Miller’s farm.
Stellaris is set to expand again with a new small DLC named 'Humanoids Species Pack', there's also a bunch of news in relation to the next major patch.
Few games make me excited beyond help, especially when they're on Kickstarter, but space drone building game Nimbatus is fully funded and coming to Linux. I tested it and I love it.
Warhammer 40,000: Gladius - Relics of War is a new 4X turn-based strategy game from developer Proxy Studios and publisher Slitherine, seems it's coming to Linux too!
Oxygen Not Included is the space colony simulation game from Klei Entertainment that I'm pretty excited about and it's showing signs of life for a Linux port.