With Adventure Time ending it's nine-season run in 2018, Frank Seibert, one of the creative minds behind the series, may have found his next project in an old video game. Seibert said on an Nickelodeon podcast that he was working on a super violent animated project based on one of the most world-famous video games of the last 30 years. This work is being done under his Federated Studios banner which does Adventure Time and The Fairly OddParents. They also have the adaptation rights for Castlevania, and have had them for the last decade.
There's not a whole lot of dots to connect there.
Here is the full podcast: