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.
Vagrus - The Riven Realms from the studio Lost Pilgrims is a turn-based RPG experience they claim is like "Sunless Sea meets Darkest Dungeon", set in a post-apocalyptic fantasy world.
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.
The creative platformer DASH: Danger Action Speed Heroes is releasing soon but for those interested in help to test, you can quite easily grab a beta key.
Black Mesa, the fan-made Early Access recreation of the original Half-Life is still progressing towards finishing the final content and it's looking damn good.
Pandemic Express - Zombie Escape puts you and up to 30 people in a large open-world as you try to escape on a train and it just went into Early Access today.
Tea, Earl Grey, Hot. These are the voyages of the starship Venture in Space Impossible, an open-world sandbox space adventure where every block matters.
After re-working major gameplay systems to make everything more interesting, Fort Triumph had the story campaign removed while it was adjusted. A new update is out, with it back in and there's plenty of other changes making it very interesting.
Developed by Mi-Clos Studio (Out There) and Goblinz Studio (Robothorium, Dungeon Rushers), Sigma Theory: Global Cold War, a game about using special agents to attempt control of the world has entered Early Access with Linux support recently.