Like the idea, it`s a little bit like a GunGame mode in CS
If you continue working on it I have a few suggestions:
The sword and spear felt like their damage was instant and not linked to the animation - I don`t know if that is on purpose. Also you could add some directional hint for the player where the next box is so you can speed up the gameplay a little. And last thing maybe let the camera lead a little the movement of the player - often times I felt like jumping in the dark and hoping for the best.
If you get a chance try out my game and leave some critisism^^