Well this isn't something that is going to happen or anything just me giving out a opinion to what I believe should be added in a Sonic game.
Though most games that you tend to go out on a journey or discover something you are given a character mostly already with his or her own design and the only option you have is to name the character how ever you want. Some examples are games like Blue Dragon, or Pokemon, or even in some online games.
But in some games you get the option of creating your own character in the game, giving the player the freedom to express themselves by creating a character of their own which in my opinion I enjoy doing because one can be original in the character. Examples are Lego, Dragon ball, Pokemon (X and Y), Sims, heck even the 3Ds have the Mii and even offer mini games to customize them more.
The main idea is its fun and great to create a character in the franchise and have them interact with your favorite characters of the series which actually makes it feel like a real adventure in having you involve. Dragon Ball Xenoverse can be a great example though your not exactly in the story line involve in most of the story but you get to go in it, in some points to make the story right. (I won't give out spoilers or anything because I actually recommend this game for all of you who enjoy being part of a story of a anime or just like to customize and have yourself involve in the story in a way) But the thing is it all has to do with the story of the anime in a way.
Now I think you might all ask what does all that have to do with the title? Well with my recent encounter of games that are now giving you the freedom to create your character the Sonic games are one of the many exceptions. Though it can be reasonable since many players just want to play as their favorite characters like Sonic, or Knuckles, or even Tails. But I am sure many Sonic fans have been asking for a game where they could create their own characters. For me it be fun to be involve in this game universe and have a adventure with the Sonic team and even interact with various characters. And I assure you it be one good selling game for SEGA.
Just imagine the variations of species you can choose to create your own character and even the variation of stuff you can do to create your own character. Or even a choice to be a good or a bad guy.
Question: Do you likw this idea? What would your character be and look like? What purpose could he/she have to be involve in a adventure with Sonic/Eggman?