This app is perfect for in-between. But if you're not careful, it can happen fast, that one is so much under the spell that you forget everything around you. So watch out for example on the train, that you get out will not forget. Conceptually, it is actually quite simple, as you just have to connect with each box, but by growing adventitious rules (for example different colors or fields that have to be crossed several times), it is always tricky. For puzzle fans (especially fans of Bridge Puzzles / Hashi) ie an absolute Pflichtapp and definitely worth the money.
