User blog comment:Speeddasher/Future Sonic Games. What do you want to see?/@comment-5159692-20120607204659/@comment-4802891-20120608232320

Yes, that was Sonic '06... it has all the main components of the series: a deep story, a monster-of-the-week, a lot of playable characters, various gameplay ideas, upgrade items, hub-worlds and action stages.

And, also sharing those elements, Sonic World Adventure (Unleashed) is basically Sonic Adventure 4.