Jumping on the Sonic bandwagon here. Sonic 4 was a step in the right direction, but they need to do more to restore him to his former glory. I like the idea MovieBob had in his Game Overthinker series to cull the cast as one step. They've just got too many characters. Keep Sonic himself, Tails, Knuckles, Amy Rose, and for the bad guys, Eggman and Shadow, and can the rest of them. No Cream, no Big, no Chao, no Rouge, no Silver, the list goes on. Well, maybe keep the Chaotix crew, too. Also, pick one story as canon, and one gameplay style (preferably the style from the Genesis games and Sonic 4) and stick with it. The more you try to screw with what worked, the more of an unplayable mess it becomes. Innovation is good and all, but keep the innovation within certain boundaries. Speed-based gameplay doesn't work too well with open-world 3-D environments, especially with a moveset like Sonic's. Mario's transition to 3-D worked well because Mario's platforming isn't built around speed and momentum so much as good timing. If they're really insistent on keeping Sonic in 3-D, one thing I will say worked decently well were the Sonic and Shadow levels of Sonic Adventure 2. They did offer a good blend of speed and platforming, and while they could have been designed better, were pretty good for what they had to work with. That style could be built upon to provide some pretty cool gameplay. Anyway, those are just my two cents on that.