You had passed out previously while playing a supposedly normal game of Sonic... but now you've woken up in... Green Hill Zone? This certainly is the place...

As you get your bearings, you look down at your hands... Wait. Those aren't your hands. Those aren't your legs, either. If anything, you're a Mobian now for... some reason.

As you try to understand what is going on... you see the blue blur himself, his back turned to you...