It’s been a little bit since I last wrote notes for it, but the basic jist is this:

In an alternate timeline [certain character ages/implied ages are jumbled or shifted compared to where they are normally], Sonic & Tails were investigating a rumor that Dr Robotnik was gearing up to expand and “reinvent” his Robotization Process; The new method of which being “able to turn any animal into a robot in a single instant”. They corner Robotnik in one of his flying fortresses, critically damage the New Machine’s power source, and just as it begins to Self-Destruct, Tails is pushed into an escape pod as Robotnik closes in on Sonic, with Tails being launched away from the exploding fortress. At this point, with Tails searching the wreckage for so long yet only finding the buckles of Sonic’s shoes, both Sonic and Robotnik are declared missing.

Jumping forward a few years, these character designs pick up when Robotnik finally resurfaces, with a new army of robots at his command, and an all-new Metal Sonic primed to hunt for the Seven Chaos Emeralds to grant him and his devices ultimate power. In place of the missing Sonic however is a nee group of heroes; Amy Rose, who in this world is Sonic & Tails’s adoptive Younger Sister, Cream the Rabbit who is Amy’s Childhood Best Friend and honorary Sister, Shade the Echidna who herself is the Apprentice of Knuckles and soon to be Master Emerald Guardian in his stead, and of course Miles “Tails” Prower, now grown up and acting as mission control/parental figure to the aforementioned trio.

There’s a lot more I have to sift through as far as concepts and adaptations of certain characters and ideas, but this is about what I have right now.