Really liked the concept of the game, can see a lot of potential. If you do go forward with this, these are the things I personally would like to see polished and refined.
The tileset was really busy and the character's didn't stand out from the environment all too well. Would love to see these two things improved on to increase visual clarity.
Beginning felt like a whole lot of mechanics being dumped onto me all at once. Would liked to have see something a bit more gradual with how they were introduced and taught to the player.
The box physics were very unpredictable. Changing the size of the box would move it out of position with no real options to move it back into place, and at one point even pushed my character out of the level completely.
The combat didn't feel that great. Seemed like I was getting hit by the enemies before their attack animation even started playing. Would love to see some more telegraphing in their attacks.
Really impressive entry for a game jam! Great job!