The idea of picross but with multiple layers that you need to work through is a pretty good one, but unfortunately it's let down here by the puzzle difficulty being pretty slow to ramp up, and the interface being not very good. It's very easy to make accidental inputs, which the game always punishes you for - there's no Free Mode here ala Picross DS. Additionally, as puzzles become larger they come more unwieldy on phone screens. A good idea, but badly executed.