Game guide · YOUDIYOU
Learn the rules of Classic Sudoku
Take a moment with Classic Sudoku before moving to another game. Fill all cells with 1–9; do not repeat a symbol in any row, column or region. Check the relevant rule before repeating a move. Check the rule that explains your first action. Use the example below to understand a decision.
Practice beyond the first move
Watch the feedback after an action. A message can explain whether the input was accepted or whether a rule needs attention. Refer to the controls when needed.
What you are aiming for
Fill all cells with 1–9; do not repeat a symbol in any row, column or region. Keep that objective in view throughout the round. Return to the instructions when a step is unclear.
Step by step
- 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.
Keyboard and screen 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. Keep the playing area visible while using these controls. Read the example below alongside these instructions.
A useful example
On one puzzle in this collection, row 1, column 2 has 9 in its solution. Read the clues on your current board before using that value; another puzzle can need a different entry. Compare this with the rule that governs the move. Notice the change in the playing area.
Pay attention to this rule
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. Locate the buttons and input area before beginning a long round. Use the on-screen labels to avoid an accidental restart.
A few questions answered
Before I begin, what is the goal of Classic Sudoku?
Fill all cells with 1–9; do not repeat a symbol in any row, column or region.
Before I begin, how do I control Classic 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.
Before I begin, what example helps explain Classic Sudoku?
On one puzzle in this collection, row 1, column 3 has 2 in its solution. Read the clues on your current board before using that value; another puzzle can need a different entry.
When I return, what should I watch out for in Classic Sudoku?
The key detail is this: Notes are reminders, not final entries. A full board only counts as complete when it satisfies every rule.
Before I begin, what format does Classic Sudoku offer?
Play using the solo mode shown on this page. Read the controls before starting a new round.
For my first round, which play mode does Classic Sudoku use?
The mode on this page is Solo. Same-device play uses one screen; this game library does not provide internet matchmaking.
Where should I start with Classic Sudoku?
Select an empty cell. The original clues cannot be edited.
Do I need an account or a payment for Classic Sudoku?
Here is the relevant explanation: No player account or payment is needed. Game scores are recreational results, not cash prizes.
When I return, how can I find Classic Sudoku again?
For clarity: Use the Games list or save this game page in your browser bookmarks. The Guide is linked from the playing page.
While learning, how do I report an issue with Classic Sudoku?
Here is the relevant explanation: 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.
