Give me my ‘su doku’ or I’ll sue

There's a new craze across the Pond: People in the U.K. are going mad over su doku, a Japanese puzzle that has taken the country by storm. Think of it as a crossword puzzle, but with numbers instead of letters.

I think I'll stick to the one with letters—although, truth be told, I've never seen a su doku puzzle, so perhaps I don't know what I'm missing.