Fill the grid in Sudoku
Sudoku is the world's favourite number puzzle. You're given a 9×9 grid partly filled with digits; complete it so that every row, every column and every 3×3 box contains the numbers 1 through 9 exactly once. No arithmetic — just pure logic.
How to play
Sudoku in 4 steps
Pick a cell
Tap or click an empty square in the grid to select it.
Enter a number
Type 1–9 (or use the number pad) to place a digit. Press 0 / Backspace to clear it.
Follow the one rule
Each digit 1–9 must appear exactly once in every row, every column and every bold 3×3 box.
Complete the grid
Fill every cell correctly to solve the puzzle. Toggle notes to pencil in candidates while you think.
Controls
- Click / Tap
- Select a cell
- 1–9
- Place a digit (or a note in notes mode)
- 0 / Backspace
- Clear the selected cell
- N
- Toggle pencil-notes mode
- R
- New puzzle
Strategy
Tips & strategy
Hunt for forced cells
Scan rows, columns and boxes for a square where only one digit can legally fit. Those "naked singles" are free progress.
Use pencil notes
Jot the possible candidates into empty cells. When a candidate appears only once in a unit, it must go there.
Cross-hatch the boxes
For each digit, sweep across rows and columns to see which cells in a box it can't occupy — often only one remains.
Never guess
A proper Sudoku is always solvable by logic alone. If you're stuck, look for a new pattern rather than guessing.
About Sudoku
Although it feels Japanese, modern Sudoku was designed by American Howard Garns in 1979 (as "Number Place") and only became a worldwide phenomenon after Japanese publisher Nikoli popularised it and named it Sudoku — short for a phrase meaning "the digits must be single". A 2004 appearance in a British newspaper sparked the global boom.
Sudoku is pure deductive logic: despite the numbers, no arithmetic is involved, and a well-formed puzzle has exactly one solution reachable by reasoning. The number of valid completed grids is famously enormous — over 6.6 sextillion — which is why no two puzzles ever feel quite the same.
This Unicode edition generates a fresh, guaranteed-unique puzzle every time, with four difficulty levels set by how many digits you start with. Crisp numerals, a pencil-notes mode and an optional mistake highlight keep it friendly, and your best solve time per difficulty is saved locally.
FAQ
Sudoku questions
Do I need to be good at maths?
Does every puzzle have one solution?
What are pencil notes?
How are the difficulties different?
Is my time saved?
The characters
What Sudoku is drawn with
No sprites and no canvas — this board is text. Copy the characters behind it, with their Unicode names and code points.
Support the arcade
Enjoying Sudoku?
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