This is pretty cool and not too tough. I really enjoyed firing tons of rockets. Shooting missiles were pretty fun, though it took me a little bit to realize that they ran out and I had to let them restock before shooting more. I'd suggest going all out on the paper style and replacing the walls/floors with paper textures as well. Only real gripe if you might want to add one block height terrain to prevent the player from falling. Also might want to tone down the volume on the footsteps.