Very cool game! I really liked the physics, the addition of the crate and the graphics fit very well to the game style. You need to be a bit careful with using the key Z, in some countries (also in mine :D) we have QWERTZ keyboards and then X and Z are far away. I would have chosen a bit another sound, as it did not fit very well to the game. However, this is a matter of taste :).
Congratulations to this cool game! Very well done.