Play Sudoku - one of the most popular puzzle games of all time! Train your brain with four difficulty levels - beginner, medium, hard, and expert. Perfect for all skill levels. Includes unlimited free games at any difficulty level. Each game features a single unique solution that can be deduced logically - no guessing required! All puzzles have been hand-checked and guaranteed to be solvable. Built-in solver lets you know if you have entered an incorrect digit Game board is similar to the style popularized by the YouTube channel Cracking the Cryptic, where there are multiple note styles and highlighting options. Advanced note features for more difficult levels include 2 styles of notes and cell highlighting. Notes automatically update when a digit is placed. Drag to highlight multiple cells, or use a hint if you get stuck! Also options for multi-cell selection and undo/redo functionality. Please leave any feedback - we read all reviews!