Don't bother trying to save up the coins for rewards, the app seems to reset randomly for no good reason. The first time, I spent a week playing and built up over 12,000 coins, then accepted the offer to link my account to FB, only to have all those coins reset to 100. Unlinked my account hoping to get them back, but nope. Then I spent a whole other week getting my coin total back over 13,000 this time, only for it to randomly reset to 100, this time without me messing with the account linking.