Classic sudoku game for your smartphone and tablet. Features: - Four difficulty levels (easy, normal, hard, very hard). - Tutorial with several techniques (from beginner to advanced) for solving the game. - Unlimited undo and redo. - Game saving. - Notes. - Auto noting empty squares. - Auto updating notes. - Square coloring with two colors for advanced techniques. - Errors checking (manual and automatic). - Screen rotation control. Check screen rotation for playing in portrait and landscape or uncheck it for playing in the mode you prefer no matter the orientation of the screen. - Send the game to a friend via whatsApp, email, etc...