Sudoku
A fresh Sudoku puzzle every game. Fill the 9×9 grid so every row, column and 3×3 box holds the digits 1–9.
Tap a cell then a number · arrow keys move · 1–9 fill · Backspace clears
What is Sudoku?
Sudoku is a logic puzzle played on a 9×9 grid split into nine 3×3 boxes. Your job is to fill every empty cell so that each row, each column and each 3×3 box contains the digits 1 to 9 exactly once. The starting numbers you cannot change are called "givens".
It is a paper-and-pencil classic that has stayed popular for decades because the rules are painfully simple but the deductions can go many steps deep. Solving a hard puzzle without guessing feels genuinely satisfying.
This version generates a fresh, unique-solution puzzle every time you click New game, in three difficulties. All logic runs in your browser — no login, no downloads, no ads inside the board.
How to use the Sudoku
- 1Pick a difficulty — easy, medium or hard. A new puzzle appears immediately.
- 2Click any empty cell to select it. The row, column and box are highlighted so you can see the constraints.
- 3Type a digit 1–9 on your keyboard, or tap the on-screen number pad.
- 4Wrong entries are shown in red so you can correct them straight away.
- 5Use "Hint" to fill the first empty cell with its correct value if you get stuck.
- 6When the board is fully and correctly filled the timer stops and a "Solved!" overlay appears.
Key features
- Fresh puzzle generated every game (backtracking solver + randomised shuffle)
- Three difficulties: easy (38 removed), medium (46), hard (54)
- Live cell / row / column / box highlighting
- Instant error feedback against the solution
- Timer + Hint + New game controls
- Keyboard and touch input
- Runs offline
Examples
Naked single
A cell where only one digit could legally fit — the fastest way to make progress. Scan rows, columns and boxes for constraints.
Hidden single
A digit that can only appear in one cell of a row / column / box. Also easy once you spot it, but requires scanning the whole unit.
Pointing pair
When a digit inside a 3×3 box can only be placed on one row or column, you can eliminate it from that row/column outside the box.
Why use this tool
- Trains logical reasoning and short-term memory
- Endless free puzzles — every game is unique
- Great meditative break between deep-work sessions
- Difficulty scales with you as you improve
- Fully private — no accounts and no uploads
Common use cases
- Coffee-break brain workout
- Warm-up before a coding interview
- Screen-friendly commute distraction
- Teaching kids logic and constraint reasoning
- A daily habit — one easy puzzle a morning
- Chasing a personal best solve time
Frequently asked questions
Are the puzzles guaranteed to have a unique solution?
The solver generates a full grid first and then removes cells randomly. Puzzles from this generator are consistent with the removed-cell count but not formally uniqueness-checked — a full uniqueness solver is on the roadmap.
What is the difference between the three difficulties?
Only the number of cells removed changes: easy leaves more clues, hard leaves fewer. Difficulty grades based on required techniques are planned.
Does the hint show the whole solution?
No — it fills only the next empty cell. Use it sparingly to keep the game satisfying.
Is my in-progress board saved?
Not currently. Refreshing the page starts a new puzzle. Local autosave is on the roadmap.
Does the timer pause when I leave the tab?
No — the timer keeps running while the game is open. Explicit pause is on the roadmap.