Sudoku

Sudoku is a logic puzzle played on a 9x9 grid. The goal is simple: fill every row, column, and 3x3 box with the numbers 1 through 9, with no repeats anywhere. No math and no guessing required — every well-formed puzzle can be solved through logic alone, working from the numbers already given.

How to Play

Start by looking at the numbers already filled in. Scan each row, column, and box to figure out which digits are missing, and look for cells where only one number can possibly fit — these are the easiest to solve first. As you fill in more of the grid, use elimination to narrow down the possibilities in the remaining cells. If a cell could still be more than one number, use the notes feature to jot down the candidates rather than guessing, then come back to it as the rest of the grid fills in.

Difficulty Levels

Five difficulty levels are available, from an easygoing introduction for new players up to a genuine challenge for experienced solvers. Lower difficulties start you with more filled-in numbers and rely mostly on simple scanning and elimination. Higher difficulties give you fewer starting clues and expect more advanced deduction, so you'll lean more on notes to track candidates as you work through the grid.

Features

• Notes: Mark possible candidates in a cell instead of committing to a guess, so you can track your thinking as the puzzle unfolds.
• Hint: Stuck on a cell? Get a nudge in the right direction without giving away the whole puzzle.
• Pause: Step away and pick the puzzle back up right where you left off.
• Play anywhere: Works right in your browser on both desktop and mobile, with no download needed.

A Bit of History

Sudoku's numbered-grid format first appeared in puzzle books under the name "Number Place" before the Japanese puzzle publisher Nikoli popularized it under the name "Sudoku" in the 1980s. It's worth noting that variants like Killer Sudoku, Jigsaw Sudoku, and Sudoku-X use the same grid concept but add different rules — they're related puzzles, not just other names for classic Sudoku.

FAQ

How many difficulty levels are there?

Five, ranging from beginner-friendly to expert.

Do I need to download anything to play?

No. Sudoku runs directly in your browser on both desktop and mobile.

What's the difference between Sudoku and Killer Sudoku?

Classic Sudoku only requires each row, column, and box to contain 1–9 without repeats. Killer Sudoku adds "cages" with sum totals on top of those same rules, making it a distinct puzzle rather than another name for the same game.

Is there a hint if I get stuck?

Yes, a built-in hint feature is available whenever you need a nudge.