Created by Nikoli, the Japanese company that invented the game, the puzzles in this calendar stand apart for their originality, intelligence, and elegance. They are not generated by computer--rather, they're crafted by actual Sudoku masters who know how to find the perfect balance between toughness and solvability, keeping puzzlers hooked. Easier challenges are featured each weekend, and the difficulty level increases over the course of the week. If the Sudoku master wins out, no worries--answers are on the reverse side of each page. Printed on responsibly sourced paper and 100% recyclable.