There's a lot of stuff missing for whatever reason, so I'll just paste it as it looks: It's a similar problem though, whereupon pressing 'Save & Play', and only that button, it says there is an Unhandled Exception. As a result, the software does not work unless the user provides their own copy of Sonic Mania, obtained by their own legal means.So, I'm not having the problem that other people have been having with not putting their mod files in the same folder as the exe I've already tried that. It does not contain any kind of art (music, graphics) or level layouts from the original game.

This software contains decompiled code from Sonic Mania, made by Sega Corporation and Evening Star, which was adapted to run natively in Linux-based operating systems. The information acquired through the acts permitted under paragraph (1), and the means permitted under paragraph (2), may be made available to others if the person referred to in paragraph (1) or (2), as the case may be, provides such information or means solely for the purpose of enabling interoperability of an independently created computer program with other programs, and to the extent that doing so does not constitute infringement under this title or violate applicable law other than this section.

The Digital Millenium Copyright Act of 1998, in Section 103(f)(3) regarding Reverse Engineering states: This software is distributed under Fair Use. To play this decompilation, you neeed to own a Steam copy of Sonic Mania (or Plus). It allows to run this game natively, and facilitates the installation and development of mods.

A launcher for the decompilation of Retro Engine v5, used in Sonic Mania Plus.

Sonic mania plus mod manager download