A developer from the Unsung Warriors team emailed in about their 2D action-adventure. They've released a free prologue with Linux support and it's pretty good.

Features:

Single player & couch co-op mode

Explore a beautiful handcrafted 2D world

Battle against ferocious enemies

Equip different types of weapons and items

Buy or sell equipment at a shop (no in-app purchases)

Discover various secret areas

Use your skills and reflexes to survive

Keyboard, touchscreen & controller support (rumble included)

The demo works really nicely, including with the Steam Controller when paired with SC Controller. Smooth responsive controls, some fun combat and a pretty pleasing visual style. While it's technically just a demo for a full game that will go to crowdfunding sometime, the developer told me they're calling it a prologue since it has a story of its own.

Definitely interested to see how the will expand the world and the gameplay. Grab the free prologue from itch.io and do let us know what you think in the comments.