Mach Speed.
In Sonic 06,Their are these sections called “Mach Speed” Stages by fans or “Super Speed” Stages but I don’t Think That Was Cool Enough. Anyways, these stages would have sonic go at light speeds and it’s your job to dodge the obstacles that you can hardly see beacuse your going so fast.However, this is not the first appearance of this mechanic. In Sonic Adventure, the fifth stage in sonic story that is “speed highway”, their is a part before that “at dawn” section. You take a rocket up to a tower. Once the tower loads, you’ll see a window with glass on all sides in front of you. As you might assume, you’ll have to bust the bottom, then fall down and then you run down the tower really fast. Like in Sonic 06. Dodging obstacles Like in Sonic 06. So I don’t think people would count this but that’s what I think is the first appearance of “Mach Speed”.