What a cute and polished game! Love the duck so much and all the shading!
But with all that I kinda got lost on what to do with the door? I flicked the hidden lever but i didn't see anything change? So maybe adding an arrow on where to go would be nice!
Also on the 2nD level where you have to drop the box on a button I couln't see the button at first so maybe try to make it more visible!
Other than all this amazing game visual and music to!