Cool concept and cool game! the visuals are great also. It took me a while to understand the meaning of the pink square but once I did it felt great. I was a bit confused on what to do after the first stage and didn't understand what to do but eventually I made it to the second stage.
Also I think that aiming in just one direction is pretty challenging but it still was fun, maybe the fact that the player makes a lot of bullets compensate that fact. Generally I think that it fits the theme perfectly and it is a fun game and also a very creative one :)