Daily Sudoku

How to play

In short

• Fill in the numbers 1 to 9 so that each one appears exactly once in every row, column and 3 × 3 box.
• Pick an empty square, then a number. The numbers of the puzzle itself cannot be changed.
• Every day there are three new puzzles, easy, medium and hard, the same for everyone.

Goal

The grid has 9 rows, 9 columns and 9 boxes of 3 × 3, separated by thicker lines. In the end every row, column and box must contain each number from 1 to 9 exactly once. Every puzzle has a single correct solution and can be solved by reasoning, without guessing.

How to play

1. Tap or click an empty square. Its row, column and box light up, together with all matching numbers.
2. Pick a number on the number pad below the grid, next to it on a wide screen, or type it on the keyboard.
3. If a number repeats in a row, column or box, it turns red and the game tells you where the same number already is.
4. The small number in the corner of each key shows how many of that number are still missing. When all nine are on the grid, the key gets a tick.

Notes

The Notes switch lets you write small numbers, the candidates that might belong in a square. Pressing the same number again removes the note. When you write a number into a square, the game removes it from the notes in its row, column and box. You can also see the notes of the selected square on the number pad: their keys are green.

Helpers

• Undo takes back the last move, including note changes.
• Hint marks a square where the next number can go and tells you why. The button then says Fill in, and pressing it again fills the number in. If there is a wrong number somewhere, the hint shows that first.
• Mistake check in Settings marks every number that does not match the solution right away. It is off by default.
• Time is measured from your first tap on the grid, and only while the game is on screen. You see it during play if you turn it on in Settings. After solving you always see it.

Difficulty

• Easy: you only need to find where a number fits in just one spot. Good for beginners and children.
• Medium: you need notes and techniques with pairs and triples of numbers, or the intersection of a box with a row or column.
• Hard: you also need advanced techniques such as X-Wing, Swordfish or XY-Wing.

Daily Sudoku and free play

• Daily Sudoku: three puzzles every day, one in each difficulty, the same for all players. New ones arrive at midnight (Central European time). A puzzle in progress is saved and you can continue after closing the page.
• Free play: a new puzzle in the difficulty you choose, whenever you like. The game remembers your best time for each difficulty in this browser.

Controls

• Touch and mouse: tap a square, then a number. The Erase key removes a number.
• Keyboard: move around the grid with the arrow keys, type 1 to 9, erase with Backspace, Delete or 0, press N to switch notes on and off, Ctrl+Z to undo and Esc to clear the selection.