Here is an overview of the game, via its Steam page:

Hack and slash your way through the Rotwood in this roguelike dungeon crawler developed by Klei.

Explore and fight through a labyrinthian maze of dense forest and vicious vegetation with up to three of your friends. Forge your path through ever-increasing challenges and rewards to bring the spoils of your adventure back and craft new weapons and armor or fortify your safe haven.

Watch the announcement trailer below.