Game guide · SYNTAXCODER
The essentials of playing Diagonal Sudoku
Take a moment with Diagonal Sudoku before moving to another game. 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 the game area visible while you use its controls. Identify the playing area and the controls you need. Choose a clear next step rather than rushing through the instructions.
Practice with a purpose
Read one step at a time and try it on the playing area. Match the instruction to the control you use. Refer to the controls when needed.
The purpose of your moves
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 instructions to see which actions move you towards it. Check the rules when you are unsure.
The steps to play
- Select an empty cell. The original clues cannot be edited.
- Choose a symbol from the number pad, or type it on a keyboard.
- Turn Notes on to record candidate symbols without committing an answer.
- Use Check entries to check your filled values. Hint reveals one value from the verified solution.
- Complete the board, or choose New puzzle for another board.
Getting comfortable with the 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. Read a button’s label before selecting it. Look at the feedback after the action.
Try this example
On one puzzle in this collection, row 1, column 3 has 1 in its solution. Read the clues on your current board before using that value; another puzzle can need a different entry. Your next round may have a different position, so inspect it before acting. Read the matching step again.
Where a round can go wrong
Notes are reminders, not final entries. A full board only counts as complete when it satisfies every rule. A different version of the game may use a different rule. Compare the worked example with your own position. Use the reasoning, not an answer copied from a different board.
A few questions answered
For this browser game, what is the goal of Diagonal Sudoku?
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.
How do I control Diagonal Sudoku?
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.
For this browser game, what example helps explain Diagonal Sudoku?
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.
While reading the Guide, what should I watch out for in Diagonal Sudoku?
Keep this in mind: Notes are reminders, not final entries. A full board only counts as complete when it satisfies every rule.
While learning, what format does Diagonal Sudoku offer?
For clarity: Play using the solo mode shown on this page. Read the controls before starting a new round.
When I return, which play mode does Diagonal Sudoku use?
Keep this in mind: The mode on this page is Solo. Same-device play uses one screen; this game library does not provide internet matchmaking.
For my first round, where should I start with Diagonal Sudoku?
Keep this in mind: Select an empty cell. The original clues cannot be edited.
When I return, do I need an account or a payment for Diagonal Sudoku?
Here is the relevant explanation: No player account or payment is needed. Game scores are recreational results, not cash prizes.
As a new player, how can I find Diagonal Sudoku again?
Keep this in mind: Use the Games list or save this game page in your browser bookmarks. The Guide is linked from the playing page.
For my first round, how do I report an issue with Diagonal Sudoku?
Use the contact form and include the game name, browser, device and the actions that led to the issue. Do not send passwords or payment details.