Sudoku
Fill a 9×9 grid so every row, column, and 3×3 box contains the digits 1–9 without repeats. Choose Easy, Medium, or Hard; each level starts with its own fixed set of clues.
World and Mission
The board is a self-contained number puzzle: fixed clues narrow the choices in each row, column, and 3×3 box. The same rule applies everywhere, so one placement can help resolve more than one part of the grid.
Easy, Medium, and Hard use the same solved grid with different clue patterns. Hard begins with fewer numbers visible, so you must carry more deductions forward before a cell is settled.
How the Systems Work
Select an editable cell and enter a digit from 1 to 9. The given cells are locked; Clear removes an entry you made.
A repeated digit in the selected cell's row, column, or 3×3 box is rejected with feedback. A completed board must contain all 81 digits with no duplicates in any of those groups.
Hint highlights one editable cell that still needs attention, but does not enter a digit. Undo restores your previous entry; New Puzzle resets the current difficulty's starting board.
There is no countdown. Your current entries and undo history are temporary and are discarded when you leave. Locale and sound preferences are stored in this browser; no account or purchase is required.
How to Play
- Choose Easy, Medium, or Hard, then start the puzzle.
- Pick an empty cell and scan its row, column, and 3×3 box for digits that are already used.
- Enter a possible digit with the keypad. Use Clear or Undo to revise an entry; use Hint to mark one cell to review.
- Fill all 81 cells without repeating a digit in any row, column, or box to reach the solved Result.
Strategy Tips
- Start with a row, column, or box that already contains many clues; it leaves fewer candidates to compare.
- If one digit has only one possible cell in a 3×3 box, place it before checking wider patterns.
- After a placement, rescan the crossing row, column, and box. One digit can narrow all three at once.
- Use Hint to locate a cell that needs attention, then do the deduction yourself; it does not fill the answer.
Campaign and Difficulty Growth
This is one 9×9 puzzle with three clue densities, not a stage campaign. Easy shows the most starting digits, Medium fewer, and Hard the fewest.
The board rules stay fixed across difficulties. The added challenge comes from having to compare more candidates before finding a legal placement; there is no timer or unlock track.
Developer Design Note
Sudoku keeps one familiar 9×9 board across its difficulty choices. Row, column, and box checks give immediate feedback, while Hint points to a cell to review without completing the deduction for you.
Player and Save Information
Sudoku is a number puzzle for a general audience. No sign-in or purchase is required. Current board entries and Undo history are not saved and are discarded when you leave; locale and sound preferences stay in this browser and may be removed with its site data.
FAQ
- What makes a number legal?
- It must not already appear in that cell's row, column, or 3×3 box.
- What changes between Easy, Medium, and Hard?
- Each difficulty uses a different set of starting clues on the same 9×9 solved grid. Hard begins with fewer clues.
- What does Hint do?
- It highlights an editable cell that needs attention. It does not enter a digit for you.
- Does New Puzzle create a different board?
- No. It resets the selected difficulty's starting board; this version uses a fixed solved grid rather than generating a new one.
- How do I complete the puzzle?
- Fill all 81 cells so each row, column, and 3×3 box contains 1–9 without repeats.
- Is my current board saved?
- No. Board entries and Undo history are discarded when you leave. Only locale and sound preferences are stored in this browser.
