I enjoyed it! Loved the sound FXs.
At first I was pretty lost as to what I was trying to achieve. Without a clear goal I ended up stacking boxes as high as I could and stumbled into the ending without really understanding how I won. While the mystery of what I was suppose to do was the core of my fun, I think some context would go along way. Something telling me a goal like a opening screen with "Destroy the ..." would help keep my interest without giving away the mystery. Then when I reached the end I would have a better sense of achievement.
Pros:
Interesting split focus, trying to keeping up with the top while not losing a box can be challenging.
Decent "toy box" trying to mix the elements on top let me feel pretty creative.
Cons:
Lack of a clear Goal.No exit functionality after completing game.
All in all it was fun! Great job.