what about the game engine? might be able to recover the files by decompiling the game, just need the game engine's name since each one encrypts each game differently
got some good news, the game files are recoverable using OpenGMK/GM8Decompiler (https://github.com/OpenGMK/GM8Decompiler) you can find the releases near the bottom of the page in a blue text link labeled releases.
If you want to update the game that's up to you but I personally think it needs a little polishing up.