How to play: sudoku is a logic-based puzzle. The goal of this brain game is to fill a 9×9 grid with numbers so that each column, row, and square of the nine 3×3 contains all of the digits from 1 to 9. 3 difficulty levels from easy to hard. Hint system will help to learn how to solve the sudoku puzzle. Unlimited sudoku in 4 different difficulty settings. Unlimited redo & undo.