Features: * Millions of puzzles * 30 givens * A Timer * Unlimited hints * Save your game progress * Free upgrades * Print your puzzles as black and white worksheets * Print solution sheets (designed for teachers) Rules: 1. All blank spaces must be filled with a number from 1 to 9, 2. Each row must contain each of the numbers 1 to 9. 3. Each column must contain each of the numbers 1 to 9. 4. Each Region must contain each of the numbers 1 to 9.