Diagonal Sudoku

THE PLAYBOOK · XH0411

How to play Diagonal Sudoku

The XH0411 guide to Diagonal Sudoku starts with explain your choice. Your task is to 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. The controls and example below describe this exact implementation.

Explain your choice

Try describing the reason for a move or action in one sentence. If the reason is unclear, revisit the rules before continuing.

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.

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 useful example

Before filling a cell, compare the symbols already used in its row, column and 3 × 3 region. A candidate must be absent from all three. The two long diagonals must also contain each symbol once.

Watch out for this

Notes are reminders, not final entries. A full board only counts as complete when it satisfies every rule.

Common questions