Sudoku
About Sudoku
Sudoku is the world's favourite logic puzzle, and this free online version gives you an endless supply of fresh puzzles right in your browser on any phone, tablet or computer. The rules fit in one sentence: fill the 9Γ9 grid so that every row, every column and every 3Γ3 box contains each digit from 1 to 9 exactly once. No arithmetic is involved, only careful reasoning. Every puzzle here is generated on the spot and checked to have exactly one correct solution, so you never have to guess. Pick from four levels. Easy and Medium puzzles can be finished using only the two basic techniques every player learns first, which makes them good for a relaxed tea break or for learning the game. Hard puzzles give you fewer starting numbers and demand longer chains of reasoning, and Expert puzzles are built to need more than the basics. The board is designed to stay readable on a small screen: tap a square and its row, column and box light up, every copy of the same digit is highlighted, and a big number pad shows how many of each digit are still missing. Switch on Notes to pencil in candidates. They are cleaned up automatically when you place a digit, and use Undo and Erase freely. A wrong entry is marked in red and counts as a mistake; after three mistakes you can keep going by watching a short ad or start a new puzzle. Stuck? A hint fills in one square for you. Your progress is saved automatically after every move, and your best time for each level is kept so you can watch yourself improve.
How to play
Tap an empty square, then tap a number on the pad (or type it on a keyboard). Each row, column and 3Γ3 box must contain the digits 1 to 9 once each. Turn on Notes to add small pencil marks instead of answers. Erase clears a square, Undo takes back your last change, and Hint fills in one square after a short ad. A wrong number turns red and counts as a mistake; three mistakes end the puzzle unless you choose to keep going. The puzzle is solved when every square is filled correctly. On a keyboard: arrows move, 1 to 9 enter, Backspace erases, N toggles notes and Z undoes.
Questions
Does every puzzle have one solution?οΌ
Yes. Each puzzle is checked by a solver before you see it, so there is always exactly one correct answer that can be found by logic.
What do the difficulty levels mean?οΌ
Easy and Medium need only the basic techniques. Hard has fewer starting numbers and longer reasoning, and Expert puzzles need more advanced methods.
How do notes work?οΌ
Tap Notes, then tap numbers to add or remove small candidates in a square. When you place a digit, that digit is removed from the notes in the same row, column and box automatically.
Will I lose my game if I close the page?οΌ
No. Your current puzzle, notes, mistakes and time are saved after every move and restored when you come back.
Is this Sudoku free?οΌ
Yes. You can play as many puzzles as you like for free. Optional short ads give hints or let you continue after three mistakes.
