This is an amazing little game! I have two notes though.
1. The level selection screen is very confusing. There are no visual ques to tell the player what he is selecting which frustrated me a bit because I wanted to play 1 level in particular and couldnt find it.
2. The Z button needs some visual ques as well. Like half of the time I would press it and it wouldnt work because I was pressing arrow key before Z. You could add like an arrow to tell the player once they release the Z key an action will be made.
Overall love the art and gameplay! Keep it up.