Or to give it its full title, Adventure Time: Explore the Dungeon Because I DON’T KNOW! was announced back in the antiquity of May, and now has some screens and a video explaining the plan (below). That plan involves a "four-player co-operative multiplayer" in the Adventure Time world, with a voiceover from the original cast. You'll be involved in some ARPG sort thing, where you work through a hundred floors of a massive dungeon. Gosh.
Adventure Time: Explore the Dungeon Because I DON’T KNOW! is due for release on November 12th.