Sonic 2 Hacking Guide
Binary - Special Stage Editing

This will allow you to redesign the special stage. However, the format hasn't been found yet. You'll be better off modifying them through savestates. Anyhow, here is the information for the binary.


If you would like to change how many rings are needed for each round in a special stage, modify the bytes at this address.


This has an array list for each round -- four rounds per special stage. Rings needed per round are stored in 16-bit sized values.