Play Sudoku online — Sudoku Classic: Legacy Puzzle

Playing Sudoku in your browser

This is the full game, not a cut-down demo: the same Dart engine that runs the Android and iOS builds, compiled for the web. Puzzles are generated on your own machine, so there is no waiting on a server between grids, and nothing about how you played leaves the device.

Pick a grade and the board appears. Select a square, type a digit, and watch the row, column and box it belongs to light up along with every other square holding the same number — which is how you spot the next move without counting.

Controls

With a keyboard

• 1–9 — write that digit into the selected square, or pencil it in when Notes is on.
• Arrow keys — move the selection. It stops at the edges rather than wrapping, so you never lose your place.
• Backspace or Delete — empty the selected square.
• N — turn Notes on and off.
• H — spend one of your hints.
• Ctrl+Z (Cmd+Z on a Mac) — undo.
• Esc — pause, or close whatever dialog is open.

With a mouse or a touchscreen

Tap a square to select it, then tap a number to write it in. The small figure under each key counts how many of that digit are still missing from the grid, so a key that greys out is a digit you have finished placing. Undo, Erase, Notes and Hint sit under the board on a phone, and beside it on a wide screen.

What the game keeps

Your board, your pencil marks, the clock, your mistake count, your best times and your statistics are written to your browser's own storage after every move. Reload the page, close the tab, come back tomorrow — the run is where you left it, and Continue is waiting on the home screen. Nothing is uploaded and there is no account to make. Clearing site data for this domain erases all of it, which is exactly how it should work.

Choose a difficulty

Each grade is a real constraint on the generator, not a label. Read what each one demands before you pick:

• Easy Sudoku — Plenty of clues, and every square findable on its own. (40–47 clues, 5 hints)
• Medium Sudoku — Fewer clues, and units you have to read as a whole. (32–38 clues, 4 hints)
• Hard Sudoku — Sparse. Expect to rule things out before anything falls. (27–32 clues, 3 hints)
• Expert Sudoku — Very sparse. Long chains, and notes close to essential. (22–27 clues, 3 hints)

New to Sudoku?

Start with how to play for the one rule and the first few moves, then the rules in full for why every grid has exactly one answer. When the easy grids stop being a challenge, the strategy guide picks up where scanning leaves off. The daily challenge is the same puzzle for everyone, every day.