A calm sudoku game that respects your logic
- Every puzzle has exactly one solution and is verified by a human-style logic solver to need no guessing, then rated Easy, Medium, Hard or Expert by how much reasoning it takes.
- No error marking: entries are never turned red and there is no mistake limit. You get candidate notes, undo, pause, three hints per game and deduction help that explains the next step without changing the board.
- Works everywhere: modern browsers on iPhone, iPad, Android, Windows, macOS and Linux, with landscape and portrait layouts, full keyboard control, screen-reader support, light and dark themes.
- Installable and offline: add it to your home screen like an app; after your first visit it keeps working without a connection.
- Two languages: English and Simplified Chinese. The game follows your browser's language on the first visit.
Four sudoku modes
Classic sudoku
Every row, column and 3×3 box holds the digits 1–9 exactly once.
Jigsaw sudoku
Nine irregular regions outlined in bold replace the 3×3 boxes; each still holds 1–9 once.
Diagonal sudoku (Sudoku X)
Both long diagonals must also hold 1–9 once, on top of the Classic rules.
Killer sudoku
Digits in each dashed cage add up to its total and never repeat in the cage; almost nothing is given.
Daily challenge
Every day brings a four-stage route from Easy to Expert, with Classic, Jigsaw, Diagonal and Killer appearing once each. Everyone gets the same puzzles, the challenge resets at 00:00 UTC, and the Daily page tracks your current and best streak.
Friend battles
Create a room, choose the mode, difficulty and whether hints are allowed, and send a friend the six-character room code or invite link. You both solve the same puzzle at the same moment and the first correct solution wins. No account is needed, you can see your opponent's progress without seeing their digits, and a reload or short network drop reconnects you to the same room.
Leaderboards and accounts
Signed-in players are ranked by fastest time for every mode and difficulty, by today's daily challenge and by daily streak. The server checks each answer, the time and the hint count before a result counts. Sign in with an email code or Google to sync results and preferences, add friends by friend code and keep head-to-head records.
Learn sudoku
A three-tier course with bronze, silver and gold medals teaches the rules of each mode, then hidden singles, locked candidates and pairs, and finally X-Wing, Swordfish and XY-Wing practice on fresh puzzles.
Common questions
Is Celestial Sudoku free? Do I need to download it or sign up?
It is free and there is nothing to download. Open sudoku.liuzhaohan.com in a browser to play every solo mode, the daily challenge and friend battles. Signing in with an email code or Google adds synced results, leaderboards and friends.
Can I play sudoku on my phone?
Yes. It runs in modern browsers on iPhone, iPad, Android and computers, with dedicated landscape and portrait layouts. On a computer you can also play entirely from the keyboard.
Does the game tell me when I enter a wrong number?
No. Celestial Sudoku never marks entries as wrong and has no mistake limit, so every deduction is yours. If you are stuck, use deduction help or one of the three hints per game.
What is the difference between Killer, Jigsaw and Diagonal sudoku?
Jigsaw replaces the 3×3 boxes with nine irregular regions. Diagonal adds both long diagonals as units that hold 1–9 once. Killer adds dashed cages whose digits must add up to the cage total without repeating, and starts with almost no given digits.
Can I play offline?
Yes. After your first visit the whole game is stored on the device, so you can start new solo games, continue saved games and take tutorials without a connection. Battles, leaderboards and accounts need a connection.
More answers about controls, hints, battles and score checks are in the guide's FAQ.