I got annoyed and turned it off. A) I really dislike having to start with 'Easy' levels in order to unlock more difficult ones. It's fine if there's a choice so that those who've never played Logic Puzzles can learn to play, but for the rest of us it's dull. B) The squares are not receptive to touch so I found myself hitting it countless times in order to make a check or an X and often accidentally erased the check only to start again. Between that and C) the ads, I gave up and I'm uninstalling.