- I really love being able to choose different music for previous levels. although a pretty bad game in most people's opinions, I really loved the choice SatBK gave me to play as knuckles accompanied with his theme song. Generations did it well, with unlockable songs, and I'd love to see a return of that.
- I would love more levels set at night, with less of a focus on casino/bingo/vegas settings XD
- The Chao Garden is an obvious one, for obvious reasons
- Hub worlds, again, quite an obvious one, but I know when im done with the game, i spend plenty of time exploring, and hub worlds (especially when accompanied with hidden collectables like 'SA' would be nice)
- and Unlockable costumes or other extras (an extra ending would be ace) that make collecting all emblems/red star rings/S ranks, worthwhile in the end.