In one of Eggman's recent plans, he discovered that there was a great gem that kept the entire island alive and magical as it was. He planned on stealing the gem to become even more powerful. Sonic tried to stop him, but broke the gem by accident, causing the entire universe to collapse. The dimensions have been separated.

Sonic had to travel through space-time to save his friends and the many versions of them in every dimension.

In a specific dimension, he found Shadow, his rival, but as if he were twenty years older... In front of his eyes, a strong and formed male hedgehog, mature, muscular and tall. Not like the teenage Shadow he was used to.

Shadow turned to the blue hedgehog, and grimaced confusedly and defensively, as if he didn't know him. He grunted slightly.

"What are you looking at?" He said in a thick voice.