For me a good puzzle is one that makes you think to solve it, rather than relying on obsessive pixel hunting, obscure knowledge, or strange logic. For example, a puzzle that requires you to find a 1 pixel by 1 pixel pretzel that you have to combine with a box of dental floss and a drop of toothpaste to create a grappling hook would be considered a bad puzzle in my book! (although I'd laugh out loud if I finally figured it out
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