Electronic Brain Games: Sudoku Puzzles is part of a series of interactive books that helps you exercise your brain regularly to keep it in tip-top shape. You need a Brain Games smart pen to engage Sudoku Puzzles. The pen, an optic reader that recognizes text and images on the book pages, is sold separately as part of a package that also comes with Brain Training #1 and Picture Puzzles #1, plus a set of ear buds.