I could very well see a stand alone Sega fighting game doing well. Add a few characters from Sonic the Hedgehog at first, but then you could also add more from the Virtua Fighter series. Bring in classic characters such as Vectorman, Sketch Turner (Comix Zone), maybe someone from Streets of Rage (Preferebly Rage), and quite possibly a character from Phantasy Star and Puyo Puyo. Sakura from Sakura Wars would be great along with Joe Musashi. Bring in some of the modern characters too, such as anyone from Valkyria Chronicles, Jack Cayman and Bayonetta. (Platinum Games may have developed the games Mad World, Bayonetta and Anarchy Reigns, but Sega owns the rights to them). Add Honey from Fighting Vipers and Hornet of Fighters Megamix and you have a great roster.