Check out this article from IGN talking about it! They've confirmed that Tails is going to be added as an unlockable character! =D
Good news, fox fans, your favorite two-tailed vulpine is appearing in one of the only Sonic games he was absent from.
This does raise some continuity issues, but SEGA has already claimed that Sonic CD is a direct precursor to Sonic 4, and hey the game is about time travel, so who knows, right?
Sonic CD comes out later this year for XBLA, PSN, iOS, and Android.