Welcome to the 9 Circles of Sudoku Hell! From Merciless to Maddening to Murderous, this is a book to challenge even the most seasoned Sudokuist. By the end of t

From Nikoli, the Japanese puzzle company that created the sudoku craze, comesa title that starts at hard and goes to a level of difficulty not seen in anyprevio

Expert Sudoku is an all-new collection of handcrafted puzzles for the expert puzzle-solver. This is the book that challenges skilled solvers and Sudoku-lovers a

“The Best Puzzles Are Made by Happy Employees.” So Ad Age describes the credo of Nikoli, the Japanese puzzle company that invented the Sudoku craze and supp

Warning:Not for the Sudoku faint-of-heart! Introducing a book of extra tough, extra thorny—and extra addictive—puzzles specially designed for people with Ei