Hmm.. I was chatting with someone who was playing it earlier and he said that you get an egg when you kill a boss. I've not been getting eggs, I've just been getting the boss. Glitch?
Even after getting gold on everything I enjoy this. I decided to fling meteors every which way to watch the (teamkilling) carnage with my infinate ammo :D
There is one thing that crush the castle definitely has on you. And that is you can keep firing after passing the medal limit. Maybe remove the pass without getting a medal thing and then remove the shot cap? I just like attacking endlessly and pointlessly...