sudoku (Japanese: sū doku)

1. The objective of Sudoku is to fill a 9×9 grid with the numbers 1 through 9 so that each row, each column, and each 3×3 subgrid (9 in total) contains all the numbers from 1 to 9 without repetition.

2. Basic Rules:

(1) Row Rule: Each row must contain the numbers 1 through 9, with no repetition.

(2) Column Rule: Each column must contain the numbers 1 through 9, with no repetition.

(3) Subgrid Rule: Each 3×3 subgrid must contain the numbers 1 through 9, with no repetition.

3. How to Play: At the start of the game, some cells already contain numbers. These are the game’s “clues” and cannot be changed. Players must use these clues to deduce the correct numbers for all empty cells.

4. Instructions:

(1) Click on a blank cell to select it

(2) Click the number buttons below or use the keyboard to enter a number

(3) Click the "Clear" button or press 0, the Backspace key, or the Delete key to clear the entered number

(4) Use the "Hint" button to reveal the correct answer for the currently selected cell

(5) Use the "Check" button to verify if the current answer is correct

(6) Use the "Reset" button to reset the current game to its initial state

(7) Use the "New Game" button to start a new game

5. Game Strategy

(1) The key to solving Sudoku is logical reasoning, not guessing.

(2) Single Candidate Method: A cell has only one possible number

(3) Elimination method: Eliminate impossible numbers based on the rules for rows, columns, and 3x3 blocks

(4) Block Elimination: Use the possible positions of a number within a 3x3 block to rule out possibilities in other blocks