At the "Press Any Button" screen, hold Y + B and press Plus (Start) to unlock the Level Select menu. This menu allows you to select any level (including special stages), Sound Test, and fight the secret final Boss without getting all Chaos Emeralds. You can even play as Tails and Knuckles against the secret final Boss. To switch characters, press Y while "Sound Test" is highlighted. To add Tails to Sonic, press B while Sonic is shown under "Sound Test". When you start a stage, press X to enable Debug mode. Press B to change Sonic into different objects from the game. Press A to change Sonic into different item box types from the game. Press Y to place those objects anywhere desired. Press X again to change back to Sonic.All Chaos Emerald special stage locations
Search the indicated locations to get access to the special stages. Successfully complete the seven special stages to get all seven Chaos Emeralds. This path allows you to get all seven Chaos Emeralds and unlock Super Sonic before the end of Chemical Plant Zone - Act 1.
Collect all seven Chaos Emerald in the special stages to unlock Super Sonic.Secret final Boss and "True" ending
Collect all seven Chaos Emeralds with Sonic before completing Titanic Monarch - Act 2. After defeating the normal Boss of Titanic Monarch - Act 2, Sonic will be teleported to the true final Boss. Defeat that Boss to view the "True" ending.
Enter the "Cheat mode" code. At the level select screen, choose the final Boss option and play as Knuckles. Defeat the true final Boss as Knuckles to view a hidden ending. There will be a picture of Knuckles reading a book called "Sonic Mania & Knuckles" to the animals, with Sonic and Tails in the background. Alternatively, play &Knuckles mode with Knuckles.Medal unlockables
Earn the indicated number of medals by completing Blue Spheres special stages throughout the game to unlock the corresponding bonus:
- &Knuckles Mode: 11 medals
- Blue Spheres (play all 51 Blue Sphere stages): 32 medals
- D.A. Garden: 26 medals
- Debug Mode: 16 medals
- Insta-Shield: 6 medals
- Mean Bean: 21 medals
- Super Peel Out: 1 medal
While hanging onto any of the hook switches in Hydro City Zone, press Left(3), Right(3), Up(3) to have the gear boost pads in Hydro City play a voice clip each time you use them. If you entered the code correctly, you will hear a chime. Note: This code is a reference to Sonic And Knuckles; it is the level select code from that game.Alternate song in opening cutscene
Leave the game idle and let the intro cutscene play through once. The second time the cutscene plays, you will hear an alternate song.Infinite lives
When you enter Press Garden - Act 1, look for the first ink container you see (it spawns the hopping Badniks), stand next to it, and perform a spindash to kill the Badnik. Stop the spindash, let another Badnik come out, then kill it with the spindash. Repeat this to keep having the points stack up to give you free lives. Note: You cannot hold the spindash down -- you must release it in-between for another Badnik to spawn. Alternatively, you can use Super Sonic to stand there and do the same.