- It could use a button to mute the music (which is a bit painful) or at least a volume slider. I did okay with just muting the tab, though.
- The puzzles could have a bit more variety--spoiler alert: double click the purple one--but I have no idea how you'd do this... Maybe having marbles that only roll on diagonals, etc?
It looks like you are just coming off a long hiatus and getting back into the swing of things, though. Good luck with your future games.