Beat any of the Story modes with 100% completion to unlock the 'extras' option at the main menu, which contains cutscenes and music from the game. Getting 100% on different episodes opens up new songs in the audio menu.
Play as Shadow The Hedgehog:
Beat the Crisis City level as Sonic.
Play as Silver The Hedgehog:
Beat Silver as a boss using Sonic.
Beat Sonic, Shadow, and Silver's Story modes to unlock a fourth Episode.
Get an 'S' rank on everyone's levels, bosses, and town missions to open up Free mode.
Extra Free Mode characters:
|Miles "Tails" Prower||Beat all Town Stage missions|
|Rouge the Bat||Beat all GUN Commander missions|
|Blaze the Cat||Beat all Soleana mystery missions|
|Knuckles the Echidna||Beat all Town Stage missions with an 'S' rank|
|E-123 Omega||Beat all GUN Commander missions with an "S" rank|
|Amy Rose||Beat all Soleana mystery missions with an "S" rank|
Thanks to Revolution Readers PhantasyFil, Kloud_99, and Doooog!