Sudoku Free online game

What is it?

Sudoku is a number puzzle where you fill the empty cells of a 9×9 grid with 1 to 9 so that each number appears exactly once in every row, column and 3×3 box. No math is needed — just logic, using the given numbers as clues to narrow down each cell.

Modern Sudoku first appeared in an American puzzle magazine in 1979 under the name "Number Place", and in the 1980s a Japanese puzzle company gave it the name "Sudoku" and made it famous. Since it takes pure logic and no arithmetic, you can enjoy it even if numbers aren't your thing. Everyone solves the same daily puzzle, and your first full solve goes on the ranking.

How to play

1. Tap an empty cell, then a number below. Each row, column and 3×3 box must contain 1–9 exactly once
2. Turn on notes to pencil in possible numbers
3. Hints explain why a number must go in a cell instead of just giving the answer (+30 s each)

Playing on PC (keyboard · mouse)

On phones you tap the screen; on PC you can also use the mouse and the keys below.

Difficulty and rankings

There's a weekly ranking and an all-time ranking; the weekly one resets every Monday at midnight (Korea time). For details, see the Help.

Good to know on Hanpanmadang

• Every puzzle has a single solution and can be solved without guessing. Starting clues: 36+ on Easy, 28+ on Normal and 22+ on Hard.
• Difficulty is set by the techniques required. Easy needs only hidden singles and naked singles; Normal adds pointing, box-line reduction and pairs; Hard requires hidden pairs, triples and X-Wings.
• Hints explain the reasoning instead of giving the answer, adding 30 seconds each. If a number you entered is wrong, the hint points that cell out first.
• Duplicate numbers in the same row, column or 3×3 box are shown in red. This only checks the rules, not whether a number is correct.

Learn from examples

Common mistakes

Getting stuck by only asking what number fits a cell.

Flip it around: pick a number and look for where it can go (hidden single). Moves invisible from the cell's side often show up from the number's side.

Entering numbers on a hunch.

Every puzzle can be solved without guessing. If you're unsure, pencil in candidates with notes. A hint points out wrong numbers first (+30 s each).

Writing notes once and never updating them.

Entering a number removes it from notes in the same row, column and box automatically, but candidates ruled out by techniques must be erased by hand. Accurate notes are what make pairs and X-Wings visible.

Tips

• If two cells in the same row each have exactly the same two candidates, those two numbers belong to those two cells. Erase them from the notes of the other cells in that row (a naked pair).
• Start with rows or boxes that are already mostly filled. Fewer empty cells mean fewer remaining numbers.
• When stuck, use notes to write every possible number in each empty cell. Cells with a single candidate, or pairs where two cells share the same two numbers, will jump out.
• As soon as a cell has only one candidate left, enter it. Each number you place trims the candidates around it, so the next moves follow one after another.