The different pick styles were really cool, and all the different treasures were delightful.
My only thoughts are that the right-click on the upgrade screen might be a little forgettable (It's something that kept happening to me... >.>;;; ), and the lack of music. But these are just tiny flaws. This game is still very fun. :3
Also, 'center of the earth'?!... I... I will have to play this again later. :o