Proto Palace Zone, original Hidden Palace Zone in Sonic 2 for Android/iOS

Although the port for Android/iOS contains a finished version of the Hidden Palace Zone, inside the game you can find the original level, almost as it was before being scrapped from the original Megadrive/Genesis release. It plays the unused track #10 as well. How to play it: (click to read the steps) 1. Open the game and select "No save" 2. When the SEGA logo appears, touch every letter in order from left to right. You will hear the ring sound. 3. Keep two fingers on the screen, one in the bottom left and the other in the bottom right corner and wait for the title screen. 4. Go to the sound test, and play these tracks in order: 1, 9, 9, 2, 1, 1, 2, 4. This activates the debug mode (and is the original release date of the game btw). 5. Then play these: 03, 03, 03, 0B, 10, 10, 10, 04. 6. Select Hidden Palace Zone. The title card will show "Proto Palace Zone".