This is a ROM editor that lets you edit various aspects of the game.
Currently editable:
- Level layout
- Tilesets (load and save images and edit in an image editor)
- Object positions and types
- Level flags
- Level blocks (32x32 blocks making up the levels)
- Level names
- Static screens
- Palettes
- Tile sets
- Sprites
Still to come (in no particular order):
- Lots more UI improvements to make editing easier
- Fully removing size restrictions (currently sticking to the original game's data arenas for some parts)
- Music/SFX editing/replacement
- Adding a level select, sound test, game saves?
- Ability to add any number of levels, tilesets, etc
- Sonic 1 GG support
Downloads in the Releases section.
Feedback and discussion is welcome at this SMS Power! forum thread or you may raise issues here on GitHub.