Quote Originally Posted by Xurts View Post
I've never been able to get 100 on that either. There are plenty of other Moonstones that can be gotten later on. If you don't get it your first couple tries then just leave. That minigame has no future effect on anything, all you get is a prize for doing well.
Actually there are only two more. One of the purposes of this challenge is to find all of every item in the game with a finite quantity. Moonstones are one of them. There are three in the whole game, and in this challenge you get all three.

Edit: Actually, there are 4 moonstones in the game, but one of them you are only suppose to have temporarily, and then give it to the friendly Yan when you encounter it.