Sudoku

What is Sudoku?

Sudoku is the world's favorite logic puzzle: a 9×9 grid divided into nine 3×3 boxes, where every row, every column and every box must contain the digits 1 through 9 exactly once. There is no arithmetic involved and no guessing required: each puzzle here is generated with exactly one valid solution, so pure deduction always gets you to the end.

Every session serves a fresh medium-difficulty puzzle with roughly 37 starting clues. Your score is the time you take to solve it, plus a 30-second penalty for every wrong digit you commit to the board. Five mistakes end the run, so accuracy matters just as much as speed. In the daily challenge, everyone in the world solves the identical grid, which makes the leaderboard a straight test of solving skill.

How to play

On desktop: click a cell to select it, then type a digit from 1 to 9 to fill it in. Use the arrow keys to move around the grid, press N to toggle notes mode, and press Backspace, Delete or 0 to erase an entry. You can also click the digit pad below the board.

On mobile: tap a cell to select it, then tap a digit on the pad. The pencil button toggles notes mode for jotting down candidates, and the erase button clears a wrong entry or a cell's notes.

Selecting a cell softly highlights its row, column and box, and every copy of the same digit lights up across the grid: handy for spotting where a number can and cannot go. The digit pad shows how many of each number are still missing, and a digit fades out once all nine are placed. A digit that contradicts the solution turns red immediately, adds 30 seconds to your final score and counts toward the five-mistake limit.

Strategy tips

1. Start with the crowded regions. Rows, columns and boxes that already hold six or more digits leave few options for the rest: these are the fastest cells to lock in.
2. Scan one number at a time. Pick a digit that appears often, and trace which rows and columns already contain it. The intersections frequently leave exactly one legal cell in a box.
3. Use notes before you commit. When a cell allows two or three candidates, pencil them in. A wrong guess costs 30 seconds, so writing candidates is almost always cheaper than gambling.
4. Hunt for naked singles after every placement. Each digit you place constrains up to twenty other cells. Re-check the affected row, column and box immediately: chains of forced moves often cascade.
5. Watch the remaining counts on the pad. When a digit shows only one or two left, finishing that number is usually quick and unlocks new deductions everywhere else.

FAQ

Is every puzzle guaranteed to be solvable?

Yes. The generator removes clues only while a solver can still prove the puzzle has exactly one solution. Logic alone is always enough: you never need to guess.

How is my score calculated?

Your score is your solving time in minutes and seconds, plus 30 seconds for each wrong digit placed. Lower is better. A clean 6-minute solve therefore beats a 5-minute solve with three mistakes.

What happens if I make five mistakes?

The run ends immediately as a game over. Wrong digits are only counted when you commit a number to a cell: pencil notes are always free, which is a good reason to use them.

Is the daily challenge the same for everyone?

Yes. The daily puzzle is generated from a shared seed, so every player faces the identical grid. Your rank comes purely from speed and accuracy.

Can I play Sudoku for free?

Yes: like every game on Play, Sudoku is free in your browser on desktop and mobile, with no download or sign-up required.