A: Long story short, it's to minimize piracy and ensure an extra layer of legal protection for Sonic Mania Plus and Sonic Origins Plus. Giving players paid content for free is not the goal of this project.
A: In the Game category of settings.ini, add a tag called username and enter the desired username in it.
A: Try turning on VSync in settings.ini.
A: Submit an issue in the issues tab and we might fix it in the main branch. Don't expect any major future releases, however.
A: Sonic Origins doesn't have any music or sound effects contained in the games' data files, instead storing and handling all in-game audio itself through Hedgehog Engine 2. You can fix this by simply inserting the audio files from other versions of the games.
A: By default, the game mode is set to Classic Mode, which disables the Drop Dash. The only way to change this is through a mod, either by changing the default value of the game.playMode global variable in GameConfig.bin or by setting the variable to another value via scripts.
A: Sonic Team implemented Amy (and Knuckles in Sonic CD) in a way where they aren't playable on the decomp out of the box. This can be fixed via mods. Do not ask about this in an issue, as we will not be able to help you. There are also checks implemented in the engine to prevent playing as these characters on release builds and autobuilds.
A: There is! You can find RSDKv3 here and RSDKv4 here.
A: Absolutely not. This project took about 1 and a half years to do, and between the last two and this one, we're done with decompiling, at least for the time being. Please do not expect any more decompilations from us, Sonic or otherwise!