Start a new game in no save mode. Once the SEGA logo appears, tap the letters S, E, G, and A in that order, and a chime should sound. Then, hold two or more fingers on the screen until the level select appears.
Get All Emeralds
Start by accessing the level select menu, then navigate to the sound test in the bottom-right corner of the screen. Play sounds 04, 01, 02, 06 in order, and the "emerald-collected" sound should play. All emeralds will now be collected and the player can turn super by collecting 50 rings, then pressing the jump button twice.