Sudoku Number Puzzle

[Rules of the Sudoku (数独, すうどく) number puzzle game]

1. The name comes from the Japanese phrase, "a number can only be used once (数字は独身に限る)".

2. The game is filling 9 x 9 = 81 square-cells using numbers 1 through 9.

3. Each row or column is filled using numbers 1 through 9. The order of number doesn't matter, but all 9 number must be used only once.

4. The sum of the numbers in a row or a column should be 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 45.

5. Nine numbers 1 through 9 should also be placed in each 3x3 sub-matrix. There are total 9 3x3 sub-matrices. The sum of the numbers of a sub-matrix should be also 45.

6. This is a fun game with a long history that is simple in principle but greatly helps with brain training.

[Play Steps]

1. Select a difficulty level from 1 to 5.

2. The game will automatically start after you select a difficulty level.

3. Press the Start button to start a new game.

4. Press the DEL button to delete the numbers entered in the squares.

5. Memo OFF: Enter the number to be placed in the square.

6. Memo ON: Note down possible numbers that can be placed in the squares.

7. Remarks: You can view the game instructions, company information, and privacy policy.

* There are no interruptions while you play the game!

We sincerely hope you enjoy the game.

Thank you very much!