Legend of Dungeon is a 4 Player Co-Op Roguelike-like Beat'em'up, developed by RobotLovesKitty and set for release on multiple platforms, including Linux.
The developers from the RobotLovesKitty studio have reached out to the community for support, with the help of Kickstarter, and raised the money they needed. You can still pledge money to their game as the contribution period isn't finished yet.
According to the developers, Legend of Dungeon is about looking for treasures in a dungeon full to the brim with monsters.
Legend has it that there is a massive treasure all the way down on the 26th floor. This is the ultimate quest of the player, to make it all the way to the bottom, retrieve the treasure and come back to the surface alive.
More details about this games can be found on the official Kickstarter website.