This is such a cute and heartwarming game, and I love how original you were with your concept.
I feel like if you expanded upon this idea further this could become a really cool larger scale project! Especially if it was for multiple players (I would love to play this with my girlfriend).
Personally I think that the mechanics/gameplay could be fine-tuned a little bit more. I thought that some of the jumps were needlessly tight. Also, if you press Q while you are not standing near a box, the next time you walk over to one you will automatically drag it (I think it would feel better if pressing Q only activated the toggle if it's pressed while standing next to a box).
Other than those small critiques I really enjoyed this quite a lot!
Also, the color fade to red at the end completely melted my heart <3