TriStar Sudoku Variety Puzzle Book Series, Volume 3 by TriStar Books. This Sudoku puzzle book contains 200 random level Sudoku puzzles from easy to very hard. This is an ideal book for beginner Sudoku players or for families to get the kids involved in logical thinking. Sudoku puzzles are very relaxing to play and will help keep your mind alert. The Alzheimer's Association recommends Sudoku as a possible way to help ward off dementia later in life. Most of all Sudoku is fun and addictive!