I didn't finished it because I was too frustrated by the yellow enemies, but this is a really solid entry and still had a lot of fun.
The graphics are good, very clean and fits nicely to the mood as well as the music.
The level design is ok, but levels are at least twice as big as what they should be, make more compact levels!
The gameplay is good (jumping feels great), but as I was saying it's frustrating because one mistake and you die. The yellow thingy are bad because they are hard to avoid and can't really be killed, they should have had only 1-2 hp.
Not sure how it fits the theme but it was a nice little platforming game. Good job
edit: also the sprites are incorrectly rendered, you can see pixels from the upper sprite in some animations, in the tiles and even in the background, it didn't bother me a lot but it could have been more polished.