150 of the most fiendishly difficult, never-before-published Sudoku puzzles! The brand-new Sudoku puzzle series that puts even the most fervent players' skills to the test. There are those who play Sudoku, and there are those who step it up and play Sudoku Iron Man. Here are 150 never-before-published puzzles-the most challenging around. This book will have enthusiasts hooked, tackling grid after grid. Even the most avid Sudoku addict will be amazed at the intense challenges Sudoku Iron Man has to offer...