Acording to this: http://blogs.sega.com/usa/2010/05/26/introducing-sonic-colors/ this is going to be a racing game, like Sonic R 2, like I sed on the off topic. You race trough theme-park based stages in order to save the color wisps, little aliens that have powers, captured by... guess who? Dr.Eggman...
When you save one, you can use his power for example the blue wisp that gives you the abilitie to boost! But the best part of it all, is that is going to be as fast as Sonic Riders! Looks like loads of fun!