When made into a habit, playing Sudoku may help keep your brain 10 years younger and delay the onset of dementia. In this puzzle book, we envisioned to build puzzles for a healthy brain that are elegant to the eye, enjoyable to play, and with the right amount of challenge to maximize the player’s mental stimulation. The puzzles start easy and get progressively harder. The brain effort required to solve each Sudoku puzzle is measured on a scale from 0 to 10,000. Features: Includes more than 160 puzzles: 55 Easy, 58 Medium, 55 Hard. - Indicates on all puzzles how difficult they are relative to other puzzles. - Each puzzle is on a full page, solving is easy on your eyes. - Suitable for all levels: Beginner to Expert. - Includes instructions: Tips and tricks on how to play Sudoku the first time. - Includes solutions: All solutions included in the back of the book.