I want to develop a difficult--but also fun and memorable--puzzle, but I'm not sure how hard is too hard. I don't want to post it and everyone just think it's "confusing." You know, Einstein once said
“If you can't explain it to a six year old, you don't understand it yourself.”
I believe a good Einstein-ian approach to the writing of puzzles is the correct form when trying to win an audience with mixed levels of understanding, but how do you balance wanting to post a hard problem that will bring something new and fulfilling when solved and also be able to explain it in a way that a six year old could not only understand, but not be bored with the notion?