Su Doku ‘the crossword without words’ comes with a health warning : it is seriously addictive. Here is a third collection of 100 previously unpublished puzzles for those in need of a fix.

Four levels of difficulty with more difficult and fiendish than easy and mild puzzles. You don’t need to be a mathematical genius to solve these puzzles; it is simply a question of logic.

The Times Su Doku is the original and best. Each puzzle leads by logic to a unique solution so that no guessing is necessary.

Gould was a lawyer for 13 years in Matamata, New Zealand, before coming to Hong Kong in 1982 where he worked his way up to become Chief District Judge in 1993. He retired from the Judiciary in 1997 and, that same year, during a visit to Japan, he was in a bookstore where, not knowing how to read or speak Japanese, he was drawn to the puzzle which he first thought was a crossword. He was intrigued and later on he decided to take it with him to the United States and Britain. After his initial retirement, in efforts to pass time and sharpen his computer skills, Gould developed the computer program that generates Sudoku puzzles. Wayne Gould says retirement can now wait as Sudoku keeps him busier than ever. He travels between his different bases; Lantau and New Hampshire in the United States, where his wife Gaye is a professor of linguistics, and other parts of the world to which his new hobby has taken him. He has two children, daughter Sally, 29, and son, Scott, 27.