The levels of this hack was decent, except for the note block jungle level.
In the first castle level, the difficulty curve raised like Kebnekaise (it's a mountain) so the author should have aimed for a more balanced difficulty curve.
I find a glitch in world 1-1. Entering in a pipe you go to a underground level. When you go to other pipe to go back, you go to a unused level(Bonus background with no blocks and sprites, and the entrance is pipe up.)