Sudoku is popular the world over, possibly because of the relative simplicity of its rules. Here is huge array of sudoku puzzles ranging from the very easy to diabolically difficult. There are step-by-step instructions, and plenty of tips for all challenges.
Here is the biggest and most varied book of Sudoku puzzles ever compiled. Over 400 painstakingly prepared puzzles designed to satisfy all levels from beginner to expert. "The Mammoth Book of Sudoku" contains more challenges, more levels of difficulty, and more varieties of number-placement (and letter-placement) puzzles than any other collection available, including: huge array of easy to diabolically-difficult classic grids; monster Sudoku - multiple overlapping grids; secretly encoded alphabetical wordoku; liquid crystal Sudoku; and bonus kakro puzzles. It also contains full step-by-step instructions, tips and killer strategies from the founder of the International High IQ Society and confirmed Sudoku addict, Nathan Haselbauer.