Sudoku

Classic 9×9 number placement. Every grid is freshly generated, has exactly one solution and is solvable by pure logic.

Sudoku

The classic 9×9 number placement puzzle. Fill the grid so that every row, every column and every 3×3 box holds the digits 1 to 9 exactly once. Every grid is generated fresh for you, has exactly one solution, and can be solved by logic alone — no guessing.

How to play

1. Pick a difficulty and press Start puzzle. The puzzle code (for example #7F3A-91C2) is shown

on the start and result screens.

1. Tap a cell, then a number on the pad.
2. Every digit is checked at once. A correct digit locks in. A wrong digit turns red and counts as a

mistake; erase it or type over it.

1. Turn on Notes to pencil in candidates. A correct digit removes itself from the notes of its

row, column and box.

1. The game ends the moment the last cell is filled correctly.

The selected cell's row, column and box are shaded, matching digits light up, two equal digits in one row, column or box are marked as a conflict, and each pad key shows how many of that digit are still missing.

Difficulties

Normal, Hard

Clues at the start, 34–38, 25–29

Techniques needed, Singles only (naked and hidden singles), Singles stall; you need pointing, box/line, pairs or triples

Difficulty band, 8–16 cells that only a hidden single reveals, 2–6 steps that need those harder techniques

Mistakes, Unlimited, each adds 20 seconds, No time added, but the 3rd mistake ends the run

Hint, Adds 30 seconds, Adds 60 seconds

Every puzzle is checked before you see it: exactly one solution, the clue count of its difficulty, the technique grade above, and a difficulty measure inside the band. Anything outside is thrown away and a new grid is drawn, so all players on one leaderboard face grids of the same strength. Each of the 4,294,967,296 puzzle codes gives its own grid on each difficulty.

Time

• Your score is the clock plus penalties, to a tenth of a second. Lower is better.
• Hint fills one correct cell: the selected cell if it is open, otherwise the cell you would most

naturally solve next.

• A Hard run that ends on the 3rd mistake records no time.
• Normal and Hard have separate leaderboards.
• The clock stops while the game is paused, and the grid is hidden.

Controls

Action, Mouse and touch, Keyboard

Select a cell, Tap it, Arrow keys

Enter a digit, Number pad, 1–9

Pencil mark, Notes, then the pad, Shift + digit, or N to switch modes

Erase, Erase, 0, Delete or Backspace

Undo, Undo, U or Ctrl+Z

Hint, Hint, H

Pause, Pause button, Esc or P

The game pauses when its window loses focus. Sound, reduced motion and the interface language (English, Korean, Japanese, Chinese) can be changed at the top of the game.