Okay, so me and Hyper have been conversing and thought up the locations in our fanfic. They are from the Sonic series, and they are ones NOT included in Generations.
Sonic the Hedgehog~Labyrinth and Scrap Brain
Sonic the Hedgehog 2~Aquatic Ruin and Oil Ocean
Sonic the Hedgehog 3 and Knuckles~Hydrocity, Ice Cap, and Angel Island
Sonic CD~Palmtree Panic and Wacky Workbench
Sonic Adventure~Twinkle Park and Windy Valley
Sonic Adventure 2~Sky Rail and Pyramid Cave
Sonic Heroes~Mystic Mansion and Frog Forest
Sonic '06~Kingdom Valley and Radical Train
Sonic Unleashed~Apotos and Shamar
Sonic Colors~Aquarium Park and Starlight Carnival
Sonic and the Black Knight~Great Megalith and Titanic Plain
Sonic Chronicles~Voxai Colony and Nocturne
Sonic Advance 2~Music Plant and Ice Paradise
There we go. Here's all the main stages
REMEMBER~Only Cesar, Hyper and I are in the main team.