How to Play Cat Sudoku

The three rules

1. Every row needs 1–9. Each number appears once across the nine horizontal cells.
2. Every column needs 1–9. Each number appears once down the nine vertical cells.
3. Every 3×3 box needs 1–9. The thick lines divide the board into nine boxes.

The numbers already on the board are fixed clues. Fill the empty cells using logic: you do not need to add, multiply or calculate a score. A finished board must satisfy all three rules.

Choose a cell, then a number

Click or tap an empty cell, then choose 1–9 from the number pad. On a keyboard, use the number keys to enter a value and the arrow keys to move around the board. Starting clues cannot be edited.

Erase

Clear your entry in the selected cell. You can also press Backspace or Delete.

Undo

Reverse your last change. On a keyboard, press Ctrl + Z or ⌘ + Z.

Hint

Fill the selected editable cell correctly. Each puzzle has three hints.

New game

Start another puzzle at Easy, Medium or Hard. This replaces your current game.

The timer counts time while the puzzle page is visible and pauses when you leave the tab. Your progress saves automatically in this browser, so refreshing the page lets you resume. If browser storage is unavailable, you can still play, but your game may not survive a refresh.

A few tips for your first puzzle

• Start with a nearly full row, column or box. List the missing numbers, then check where each one can fit.
• Look in all three directions. Before entering a number, check its row, column and box. A blank cell may have only one possible value.
• Follow one number through a box. Existing copies of that number in nearby rows and columns can rule out empty cells.
• Use a hint when you are stuck. Read the filled cell in context and look for the next move it makes possible.

Red entries show a mistake to revisit. Erase the entry or use Undo, then check the three rules again. The game ends when the entire board is correctly filled.

Cat Sudoku questions