The music stopped for me after a while. Maybe it doesn't repeat? Also was kinda expecting something to happen after opening the very last door. Anyway, I really like the puzzle design. Well done.
I think I forgot the option there. Maybe a music change after every 5 to 10 level would also be nice.
I wanted to do another message, but had to fix another bugs with the other messages I made at the end and it cost me some time.
Thank you for playing and rating my game. ;)