Good music and design! I just wish some of the levels were harder, because most of the solutions are very linear and straightforward. more branching paths and more opportunities to screw you over and have to reset would be nice. Also, as you probably got the memo, one of the levels is unbeatable, so make sure to playtest the entirety of your game before submitting!
Also, incorporating Time as a mechanic with more substance would have been great, maybe give a time limit to the levels, or get creative?