Killer Su Doku poses an even greater challenge than the Fiendish Su Doku puzzles.Here are 100 previously unpublished puzzles for hard-core Su Doku addicts. Published to coincide with the launch of Killer Su Doku in the The Times this September, this takes Su Doku to the next level. The puzzles use the same 9x9 grid but there is a double challenge. The aim is not only to complete every row, column and cube so that it contains the digits 1-9, it is also necessary to ensure that the outlined cubes add up to the same number. Killer Su Doku is enormously popular in Japan and the craze will no doubt catch on in the UK.