Nice work for a game jam! I liked the game concept and the use of the theme. The physics on the boxes were a little bit funky, and the highest score I managed to get was 16.
Music and sound effects would be a nice addition.
The graphics are obviously simple, but I like the little exclamation marks you added to hint at the next box drops; a lot of games are missing this for important information off-screen and suffer because of it.