Space invader meets bowling meets rockets !
I could see this developed into a real game :)
Small nitpick : i would really have liked to see more of the rocket swarm while i'm steering it.
Also, the choices in the shop don't offer any cost-balancing dilemma for the player : they all have a 1 kill -> 1 rocket ratio, so you just use whichever is closest to your kill count. I feel there's an opportunity missed here.
Good job !