How to Play Diagonal Sudoku

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How to play Diagonal Sudoku

Choose a round of Diagonal Sudoku and settle into its rules. Fill all cells with 1–9; do not repeat a symbol in any row, column or region. The two long diagonals must also contain each symbol once. Use the example below to understand a decision. Keep the instructions close while learning this activity. Check the relevant rule before repeating a move.

Try a deliberate move

After a move, check what changed. Decide which rule explains the new state before acting again. Use the example to check your reasoning.

Your goal

Fill all cells with 1–9; do not repeat a symbol in any row, column or region. The two long diagonals must also contain each symbol once. Keep that objective in view throughout the round. Keep the controls in easy reach.

Step by step

1. Select an empty cell. The original clues cannot be edited.
2. Choose a symbol from the number pad, or type it on a keyboard.
3. Turn Notes on to record candidate symbols without committing an answer.
4. Use Check entries to check your filled values. Hint reveals one value from the verified solution.
5. Complete the board, or choose New puzzle for another board.

Controls

Tap or click a cell and use the number pad. Keyboard: arrows select cells; digits (and A–G on 16×16) enter values; Backspace erases. A careful first action helps you become familiar with the layout. Look at the feedback after the action.

A useful example

On one puzzle in this collection, row 1, column 1 has 2 in its solution. Read the clues on your current board before using that value; another puzzle can need a different entry. Apply the same reasoning to the position in your own round. Look for the relevant detail.

Watch out for this

Notes are reminders, not final entries. A full board only counts as complete when it satisfies every rule. Check the rule before repeating the action. Before your first action, say what you are trying to achieve. Then compare the result with the goal.

Common questions