Sudoku is a logic puzzle game that has been played for thousands of years. It is one of the best known brain teasers. In Sudoku, the goal is to fill a grid with numbers from 1 to 9 so that each number appears only once in each horizontal, vertical, or diagonal row.

In Sudoku, there are several ways to play. You can either play the game on your own or with the help of a computer. If you're playing with a computer, you can choose between a classic mode, which is played on a 9×9 grid, and a new mode, which is played on a 7×7 grid.