BradyGames’ Su Doku Addict Volume 2 includes the following: More than 150 puzzles! Six levels of difficulty to keep challenging users as they get better and faster at solving the puzzles. Puzzles with radial symmetry - that is, symmetry around the center box - which is a necessity for true and pure Su Doku. The puzzles in Su Doku Addict have only one solution, which is a necessity for true and pure Su Doku. Genre: Puzzle (Sudoku, Su Doku)This product is available for sale worldwide.