User blog comment:Sonic100jam/HAPPY 20th ANNIVERSARY SONIC!/@comment-3316766-20110818121057

So far, Sega and Sonic Team revealed Green Hills, Chemical Plant, Stardust Speedway, Casino Night, Launch Base, Mushroom Hills, City Escape, Seaside Hill, and Rooftop run. Now they should reveal Sky Sanctuary, Speed Highway, Crisis City, and Planet Wisp.