In this Universe, Sonic and Tails do not exist, because Eggman, the terrible villain with a thirst for world domination, created 2 robot girls with the appearance of a hedgehog and another of a fox, and called them Metal Sonic and Metal Tails, they would be his weapon of domination, but they were super powerful and betrayed and killed him

They easily managed to subjugate much of the world, but they wanted something more, the Chaos Emeralds, and so they set off on a journey to get them all, and after much effort they got 6 of the 7 and returned to base

Metal Sonic and Metal Tails were at their base happy to have almost all the Chaos Emeralds, the robot girls were celebrating because now there was only one emerald left to become Goddesses, and with the power of the 7 combined emeralds they would create the Master Emerald and transform the world into a robotic and mechanical planet to rule.

What they didn't know was that you and shadow were after the emeralds.