Replying...
Intro. It's the world of Sonic Generations, you're happy in Green Hill and Sonic is happy and invites you to his party! But at the party a strange being called a time eater takes them all to different times and the line loses its color. Then we take the perspective of classic sonic, a sonic that speaks higher pitched than modern sonic and is smaller but with almost the same maturity and desire for adventure. In the perspective of classic sonic in a 2D green hill but with the realistic touch of theme while he walks, time eater summons him together with modern sonic in this adventure saving the universe.

Sonic the Hedgehog

@Kurosakii