Sudoku
Click a cell, then type 1-9. Press N for notes mode.
How to play Sudoku
Sudoku is a number-placement puzzle on a 9×9 grid divided into nine 3×3 boxes. Fill every empty cell so that each row, each column, and each box contains the digits 1 to 9 exactly once. Every puzzle has a single solution reachable by logic alone — no guessing required.
- 1 Select an empty cell, then choose a digit from 1 to 9 to place.
- 2 Each row, column, and 3×3 box must contain 1–9 with no repeats.
- 3 Use the given numbers to deduce where each digit fits.
- 4 Complete the whole grid correctly to solve the puzzle.
Frequently asked questions
How do you solve Sudoku?
Scan rows, columns, and boxes for a digit that can only go in one cell. Start with the most-filled areas and work outward by elimination.
Is guessing ever required?
No. A proper Sudoku has exactly one solution found purely by logic; if you are guessing, there is usually a deduction you have missed.
What do the difficulty levels change?
Harder levels start with fewer given numbers and need more advanced techniques, while easier ones provide more clues.
Is every puzzle solvable?
Yes — each generated puzzle has one unique, logically reachable solution.