Extremely hard, this is one evil game! I found the challenge enjoyable equal to Hotline Miami. Since both the box and character could die and the ammo count had to be kept in mind it got quite difficult. The art style was nice and the shooting felt good.
If you iron out the kinks with the character getting stuck on the environment and the UI being a bit jerky it would have felt a lot better. I see potential for a full game here, nice job!