Sudoku description

Sudoku is a number-placement puzzle. The objective is to fill a 9×9 grid with digits so that each column, each row, and each of the nine 3×3 blocks that compose the grid contains all of the digits from 1 to 9.

Features
✓ 4 difficulty levels.
✓ Unlimited Undo and Redo.
✓ Intelligent hints
✓ Error Checking