I just found
this amazing mod featuring our boy Klonoa!
Not only does it replace Sonic with Klonoa, but it also changes the game entirely where you get 3 hits instead of relying on rings, and you need to pick enemies up to throw at others and double jump, just like in the original games! This guy went above and beyond!
While making this thread I also discovered
this other mod where Klonoa more resembles the graphical style of the game and I imagine plays more like Sonic Adventure, have yet to try it, though!
But yeah, if you have Sonic Adventure on PC, here's a new way to play it!