Play Sudoku Online
Sudoku is a sudoku game without ads, built around twenty classic nine-by-nine puzzles. Fill each row, column and three-by-three box with the digits one through nine exactly once. Starter digits stay fixed, while pencil notes give you space to reason through the empty squares.
How to play Sudoku online
- Choose an empty square and compare its row, column and three-by-three box.
- Enter a digit or use Pencil to record several possible candidates.
- Complete all rows, columns and boxes to unlock the next puzzle.
Controls
Tap a square, then a digit button. Previous and Next move between editable squares. Pencil toggles candidate notes; Erase clears a square. Undo reverses an entry. Repeated digits are marked immediately, and Check also highlights entries that disagree with the unique solution.
A tip before you start
Look for a row, column or box with only one missing digit. When several digits fit a square, keep pencil notes and use its crossing constraints to eliminate choices.
Find a forced digit in the first Sudoku board
In Sudoku Challenge 1, the fourth row has one empty square. Use that row for a first move you can explain without guessing.
- Read the fourth row from left to right: blank, 7, 2, 9, 4, 5, 1, 8, 3. The only digit missing from 1–9 is 6.
- Check the first column: its fixed digits are 3, 7, 1, 4, 9 and 2. None is 6.
- Check the middle-left 3×3 box, covering rows 4–6 and columns 1–3. Its fixed digits also contain no 6. Enter 6 in row 4, column 1.
- Recheck the affected column and box. When a later square still has several possible digits, use Pencil and compare all three groups before entering one.
| Constraint | What Challenge 1 shows | Decision |
|---|---|---|
| Row 4 | 7, 2, 9, 4, 5, 1, 8 and 3 are already present. | Only 6 is missing. |
| Column 1 | No fixed 6. | The column permits 6. |
| Middle-left 3×3 box | No fixed 6. | All three groups permit the move. |
This is a worked opening move for Challenge 1. Other levels have different starting digits; repeat the checks instead of copying the answer.
Twenty verified puzzles in a graded sequence
Every puzzle has exactly one solution. Their order increases a fixed solver’s measured work, first by branch count and then search nodes. This is a reproducible design measure rather than a claim that every person will find each puzzle harder. The hint allowance decreases from twenty to one.
A calm place to make corrections
There is no timer, lives counter or mistake limit. Use Undo and pencil notes freely, and restart a puzzle after confirming when you want a fresh board. Hint fills one editable square while hints remain.
Choose the twenty-level course or the daily puzzle
Sudoku is a fixed course of twenty puzzles with progressive unlocking. Daily Sudoku is a separate dated challenge shared by everyone opening that date, with previous dates kept in its archive. The course saves unlocked levels but resets an unfinished board after a reload; dated challenges can save unfinished entries in this browser when local storage is available.
Frequently asked questions
Is the entire sudoku game without ads free?
Yes. Every puzzle is free online with no ads and no download.
Are these smaller or variant Sudoku boards?
No. All twenty use classic 9×9 rules with nine 3×3 boxes.
Does Check fill the answer for me?
No. Check highlights conflicting or incorrect filled digits. Hint is the separate action that enters one correct digit.
How is progress saved?
Unlocked challenges, best scores and sound settings are saved in this browser when local storage is available. An unfinished board resets after a reload. Restart asks for confirmation and keeps your unlocked challenges.
Can I play on a phone or computer?
Use touch or a mouse, or focus the labeled action buttons with a keyboard. The board fits its game window and switches to a portrait layout on phones. Help opens in its own dialog, and full screen is available where supported.
Can I enter a number just because it is missing from the row?
Check the column and the 3×3 box too. All three groups must allow the number; Pencil notes can help when more than one candidate remains.
Is this the same board as Daily Sudoku?
No. This page opens the twenty-level Sudoku course. The Daily Sudoku link opens separate dated puzzles with their own browser progress and archive.
More ways to play
Play Daily Sudoku and explore the archive · Games like Sudoku.com
About Sudoku
Sudoku is a sudoku game without ads, built around twenty classic nine-by-nine puzzles. Fill each row, column and three-by-three box with the digits one through nine exactly once. Starter digits stay fixed, while pencil notes give you space to reason through the empty squares.
Play this puzzle / casual game in the embedded browser player. No app installation or MangoFun account is required. Follow the instructions shown inside the game; controls and device support depend on the title.
