Tails becomes unlocked as a playable character when you have beaten the game once.
Unlock D. A. Garden and Visual Mode:
These features become available when you have beaten the Level Time Trials in under 25 minutes.
Unlock Level Select:
This feature becomes available when you have beaten the Special Stage Time Trials in Under 5 minutes.
Unlock Sound Test:
This features becomes available when you have beaten the Special Stage Time Trials in under 4 minutes.
Enter the following codes to enable the corresponding effect.
Enter PCM12, DA11
Play Special Stage:
Enter PCM07, DA07
Enter PCM03, DA01
Enter PCM12, DA25
Sonic the Muscle Builder:
Enter PCM04, DA21
Revenge of the Mutant Artwork:
Enter PCM11, DA09
Super Spin Dash:
Hold down on the D-pad and press the 'Jump' button so Sonic spins on the spot. When you release the D-pad Sonic will move forward in a speed determined by how long the D-pad was held and perform his Super Spin Attack which is handy when you need to gain a lot of momentum in a tight spot.
Creepy Anonymous Sonic Artwork:
On Android/IOS,if you enter the codes 12(left) and 25 (right),a confirmation sound effect will be heard and show a disturbing image of sonic and the following text saying
"Fun is Infinite"
"Majin"(for devil) or 《madin》