In 2020, one year after the TAS of Kuru Kuru Kururin, I decided to investigate the code of this GBA game furthermore and make an editor that allows to edit the maps of the game! Armed with an emulator and a debugger, I tried to document where and how maps are stored, to extract the tiles and palettes for each level, etc. Finally, I managed to make a level editor! You can find it on Github (the source code is written in C#).

My friend mohoc7 used it to create an insane(ly difficult) ROM-hack that you can download here 😁 (and it works on a real GBA: I've tested it!). I also adapted the level editor to support the sequel of the game, Kururin Paradise, with some contributions from Dimedime!