Recently two British newspapers have launched the next generation of crosswords -- codebreaker grinds. Resembling a standard crossword in format, the only difference being each blank square has its own number from 1 to 26, there are virtually no clues but let me quote the Daily Mail's Codeword instructions to give you a flavour of the challenge.
Word Ways: Vol. 30
, Article 13.
Available at: http://digitalcommons.butler.edu/wordways/vol30/iss2/13