After you go through a lot of levels, it does not appear to be able to win any more. – Space Pop Shooter Review

Because of wanting to wi more levels, you have to buy coins. That is good for you, but not for me. My remedy for this problem is to quit buying coins and deleting the game. I love the game, but it is unfair, such as get through five levels and earn 5 coins, but to add coins it costs you 15 coins! Not fair!!!
Review by Mjalvis on Space Pop Shooter.