The concept of the app, in my opinion, is very interesting and exciting. I enjoyed the mechanics, slowly building up your inventory and getting closer to free little by little. Finally thinking of (or stumbling upon) the next step is exciting, though the time in between can be frustrating as you tap on every spot to try to find another hidden location or try to combine items.
The game itself deserves 4 stars, but unfortunately ads are enough of a problem to bring it down one. It's a free game and I usually don't complain about ads because, again, it's free. But in a game focused on exploring, visiting a spot multiple times and looking for a new thing it may have to offer, I couldn't think of a worse place to decide to have an ad pop up.
Multiple times as I tapped to get to another spot an ad would appear unexpectedly, and obviously before I could react I would be brought to the App Store. An irritating break in the flow of the game. And now, close to the ending (or at least I believe so :P ), I am no unable to play as an ad appears whenever I start and does not disappear no matter what, making it unplayable.
With a better system and placement for ads, the app would be much more enjoyable