BoingBoing has an article about the author's experience with an extremely expensive, extremely disappointing physical metal puzzle called Isis I that may or may not be a marketplace scam to amass a mailing list filled with rich people.

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Midway through the article, while bemoaning the way the puzzle works (or doesn't), the author provides a helpful list of rules that he feels make for a good puzzle:

  1. The objective has to be clear and easy to understand without special training.
  2. The rules under which the objective is to be achieved have to be clear and understandable without special training.
  3. The challenge presented by a puzzle must be primarily intellectual in nature, not physical. Juggling, for example, is challenging, has a clear objective, and operates under clear rules. But it's not a puzzle.
  4. And finally:

  5. The challenge must arise as a direct result of the structure of the puzzle and not from some obscured secret.

Find out the myriad ways in which the Isis I breaks these rules by reading the full article:

What's the worst puzzle you've ever tried to solve, and what made it bad? Tell us all about it in the comments!