Just a couple suggestions
It was good, but it could be great.
All you need to do is add in some old stlye game music and sound.
Like on the donkey kong games.
Also I think its unfair that the other charactors can climb up the laders and go to the second levels and you can't.
I think you should make the ladders work as well.
It sorta feels like a donkey kong game so the ladders should work a bit like it.
Just my $0.02
Hopefully you can add some sound effects in it to make it a perfect score.
Rerelease it with sound and im sure you will get in the all time favorites list.