Some of the puzzles in hard mode are different but they are the same kind as the casual, some you have to do in less moves, but the layouts are the same and some have less started out for you, like in the jigsaw type. A couple you need faster reflexes in the hard mode. All solutions are in the guide so if you get stuck, you should still be able to get through.
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How old would you be if you didn't know how old you are?