Shown below is a crossword consisting mostly of obscure words. On average, the words are short. The average number of letters per word is only 3.86. A majority of the words are probably unknown to the reader.
"A Reconstructable Crossword Puzzle,"
Word Ways: Vol. 3
, Article 18.
Available at: http://digitalcommons.butler.edu/wordways/vol3/iss1/18