Sudoku : The X-Factor

If you are addicted to Sudoku, but feel like a change, why not try this collection of 320 new Sudoku-X puzzles? This modification of the Sudoku theme imposes the additional requirement that each of the nine symbols used (normally 1 to 9, as with Sudoku) should occur just once on each main diagonal, leading to a fresh and stimulating new challenge. An introduction explains the key points about Sudoku-X, briefly discussing required solution techniques. The ‘meat’ of the book is supplied by four sets of 80 Sudoku-X puzzles at four grades of difficulty as assessed in terms of required solution techniques. More puzzles can be found on our website : - http://www.sudokasana.co.uk