My friend and i have talked about possible games that could be used in sonic. The main and first
[1]one we thought of was some sort of ninja game with the main character Espio. The evil person could be some evil ninja lord which would be the final boss. You would play as epio going through levels and destroying the little ninja minions. The charecters could include, Espio (DER), Ray, Charmy, Vector, and Mighty. All the included charecters have some role in the game where you can play as them. The last level and boss could be held in a ninja shrine. The first level woud probably be where espio live and outside of his house. I don't have any other ideas but id i come up with any, i'll be sure to add them in.
(If you are the Sonic Team and are looking at this idea feel free to use it, i didn't say this just to brag about ideas that nearly anyone can think of.)