The continued success of Sudoko means that there's a new breed of Sudoku puzzler: experienced, resourceful and ready for a greater game challenge. This group of puzzlers, which grows larger every day, is now catered for by Vertical's new line of Sudoku books. In Sudoku Hell, Japan's great puzzle mind Tetsuya Nishio has created a selection of devilishly devious games, sure to drive all those Sudoku addicts mad with pleasure.