Aaah slugs!!!! Very creative and fun idea, very hectic also. Tower Defense games have lots of good aspects but they usually turn into idle games where you don't do anything but watch, and I think that this is a very good solution to that. If I ever expanded on this, I'd combine the tower & bullet upgrades so your bullet never gets useless compared to the towers. But overall, that was a very fun and intense 4 minutes!