The Martial Arts Puzzle Series is ranked by different color belts. The Black Belt volume contains super-hard puzzles, and features sudoku variations such as overlapping grids, irregular regions, "killer" sudoku, diagonals, and more.
Get ready to fight your way to the top of the sudoku ranks! Each book in this Martial Arts sudoku series will contain 300 puzzles, with a different blend of sudoku variants depending on the difficulty level. Black Belt Sudoku Variants will feature variants with the most fiendish twists.