I used dotPeek to decompile the source (it wasn't obfuscated), and Unity Asset Bundle Extractor to browse the game objects. A lot of the game logic was written

I used dotPeek to decompile the source (it wasn't obfuscated), and Unity Asset Bundle Extractor to browse the game objects. A lot of the game logic was written in coroutines, which dotPeek exposes as state machines, so I had to do some manual work to figure out what the control flow originally was. Otoh, coroutines record the names of local variables, unlike normal methods, so it wasn't all bad. I didn't decompile the game into a working Unity project, if that's what you were thinking.