Out of nowhere, Tribute Games and Dotemu have revealed a DLC update is on the way to Teenage Mutant Ninja Turtles: Shredder's Revenge.
An official trailer (which has now been taken down) reveals how "Radical Reptiles" will add Mondo Gecko and Mona Lisa. It will also come with a free "rockin' Remix mode" of the official soundtrack, with multiple guest artists (thanks, Wario64).
As noted in the trailer above, it's apparently "available today" on Xbox One and Xbox Series X|S. And you can play this game with Xbox Game Pass.