Ftp, but I'm about to see how it plays. Puzzle to the Centre of the Earth got a bit difficult later on in the game, but I still have faith they'll do FTP right. ETA: Yeah, greaaat game! The IAPs are for the premium currency which unlocks permanent perks, and so far as I can see you only get an opportunity to get a couple every hour, but there are no timers and the game is fun!