Before mod support, the decomp project allows for the game to be ported to more systems. Tbh, I’m not completely sure what all the differences are, but the two things that matter the most are the possibility to port to other systems, and the mods that can now take advantage of the decompiled code, allowing for mod support that wouldn’t be possible on the steam version.
Yes, but you’ll have to build the decomp version yourself. It’ll be kept separate from the steam version you already have installed. Fair warning as it looks a bit complicated. Here’s a guide: https://gamebanana.com/tuts/15254
Have you looked at the github page for the mod? This was listed as a known bug:
“LOADING A SAVEDATA.BIN WITH AN AMY SLOT OUTSIDE OF EXTRA SLOT AMY WILL CRASH THE GAME UPON ENTERING MANIA MODE. BACKUP YOUR ORIGINAL SAVEDATA.BIN!!!”
Edit: Looks like this mod was made for use with the Sonic Mania Decomp, not the version of Mania you use on Steam.
https://github.com/Rubberduckycooly/Sonic-Mania-Decompilation
What’s the difference between that and steam?
Before mod support, the decomp project allows for the game to be ported to more systems. Tbh, I’m not completely sure what all the differences are, but the two things that matter the most are the possibility to port to other systems, and the mods that can now take advantage of the decompiled code, allowing for mod support that wouldn’t be possible on the steam version.
Can my steam version turn into this decomop thing?
Yes, but you’ll have to build the decomp version yourself. It’ll be kept separate from the steam version you already have installed. Fair warning as it looks a bit complicated. Here’s a guide: https://gamebanana.com/tuts/15254