Sudoku Puzzle Challenge Book - Medium to Hard Level Guarantied proper SUDOKU puzzles with only one solution per puzzle. Each puzzle increase in difficulty as you progress, which makes them challenging and fun to solve. Answers to every puzzle are provided. No guessing needed Sudoku puzzles are a proven method for enhancing logic skills. As a logic puzzle, Sudoku is also a great brain game. If you play Sudoku every day, you'll soon begin to see improvements within your concentration and overall brain power. Every puzzle in this sudoku puzzle book has been carefully checked to ensure that each puzzle has only 1 possible solution. Puzzles Brain Games for Adults - Sudoku Logic Games For Adults Medium to Hard Level, Huge Puzzles Book With Solutions ENJOY YOUR HAPPY HOLIDAYS!