Just found this game. An absolute gem of a puzzler! Highly recommended!
A question though for anyone else who's played it: It's free to download, and I'm quite a few levels into the game already, but as yet I haven't hit any IAP. The App Store page says under the title that it "offers in-app purchases", but it's not actually listing any actual IAPs further down the page like other free games do.
Surely this isn't a totally free game? Does anyone know how many levels are playable before the purchase price comes up, and how much it costs?