Solid game and fun concept. defiantly unique. I enjoyed the six-shooter idea which random die numbers, but would have liked to have this concept utilized more. i often found myself just shooting until i happened to hit the enemy with the right dice; that was usually faster then trying to manipulate my barrel to get a particular dice for a certain enemy. The power ups were meaningless and could be removed, they don't add anything and feel out of place.
The collision detection needed work or at least some extra checks. Half way through the first game I found a way to wall climb by accident and got myself easily on top of the arena wall. Fun in it's own right to keep blasting the queen from my safe perch, but probably shouldn't be possible.