This is a great game ! Your art is very clean to be honest, and the gameplay is quite nice too (even if i spent my time falling from plateforms, i'm just bad xD) . I found the double jump mechanic very clever ! It gives a real motivation to progress through the game.

The only thing is that the theme implementation could be a bit clearer to be honest, because until the end i didn't understand where you implemented the two worlds idea

All in all that's still a very good game, one of the best i've seen so far !