This is a list of all the levels I'd like to see in Sonic Generations. Some might not make it in but I'm hoping.
Sonic 1 levels: All of them.
Sonic 2 levels: Chemical Plant zone, Oil Ocean zone, & Death Egg Zone.
Sonic 3 levels: Angel Island.
Sonic & Knuckels levels: Mushroom Hill Zone.
Sonic R levels: All of them.
Sonic Adventure levels: Lost World.
Sonic Adventure 2 levels: City Escape, Prison Island, Pumpkin Hill, & Cannons Core.
Sonic Heroes levels: All of them.
Shadow the Hedgehog levels: Lethal Highway & Black Comet.
Sonic 06 levels: Crisis City & Kingdom Valley.
Sonic Unleashed levels: Spagonia.
Sonic Colors levels: All of them.