Very nice! I love physics-based gimmicks. Being able to stack boxes to avoid traps and reach new platforms sets your game apart from the rest. I also really liked the art and music.
Even though the gameplay is unique, it can also be very buggy. Sometimes spawning boxes would not work as intended: they would either be launched at great velocity towards some random direction, get stuck off-map or completely disappear. Launching projectiles was also very finicky.
There were some instances in which I was sure I could jump between some narrow platforms, but actually couldn’t (the player collider may be a bit too wide). But apart from that, I enjoyed the movement.
As somebody else already said, music was a bit glitchy, like it would stutter randomly during gameplay and even more so while viewing the map. Played on Chrome, by the way. Also, please tone down the bloom, it’s just too much.
It’s pretty clear that you ran out of time for the final boss, so this won’t affect my rating. I’ll just pretend the game ends once you open the door. Having said all that, I really appreciated how unique this was and I’m looking forward to play a bug-free version of this! Great job!