I think this one may have gone freemium. Coin doubler iap: $1.99 All of this developers games are 'free' at the moment.
My personal favorite game by mooff. I buy the coin doubler for all of their games. So much content and fun to be had with their games.
Oh.... Did not realize that. Good thing I did not purchase it before then. I've purchased the coin doubles and ad removal on some of their other games. Edit: it looks like I did purchase this one a while back. The blackmoor one as well. My favorite is 'Bearadise.'