Original Sudoku 2 by Nikoli Publishing
And that's one of the features that makes THE ORIGINAL SUDOKU BOOK 2-- and THE ORIGINAL SUDOKU, published between seasons and already with 115,000 copies in print--unique. The books celebrate the compulsive joy of Sudoku with symmetry, smartness, and elegance. They invite you to match wits with the experts, to step into the 81-cell arena with a puzzle maker who has fiendishly anticipated your next step. Fun without frustration.
Other features? More all-new puzzles--over 300, arranged from "Easy" to "Very Hard." The same chunky, easy-to-tote format, because once addicted you will be toting it around everywhere. An informative introduction that shows you how to approach and solve the puzzles. Plus an entirely new idea--an unprecedented tutorial on how to create your very own handmade Sudoku puzzles.
The obsession continues.