Super Sudoku - Play Free Online Sudoku Puzzles
Settings
Find answers to common questions about using Super Sudoku.
How do I play?
Choose a difficulty → click an empty cell → enter a digit 1–9. If you're unsure, turn on Notes to record candidates in the cell. Use Hint when stuck. Your progress is auto-saved so you can continue next time.
What's the goal of the game?
Fill the 9×9 grid with digits 1–9 so that each row, each column, and each 3×3 box contains all digits 1–9 exactly once, with no conflicts.
Can digits repeat within a row, column, or 3×3 box?
No. Each row, column, and 3×3 box must contain the digits 1–9 without repetition.
Can I change the given digits (clues)?
No. Given digits are fixed and cannot be edited.
How does Conflict Detection work?
If Conflict Detection is enabled, any invalid placement (like a duplicate in a row/column/box) is highlighted in real time so you can correct it.
What difficulty levels and puzzle count are available?
About 3000 puzzles across five difficulty levels, suitable for beginners through experts.
How do I enter or delete numbers?
Select a cell and press 1–9 on your keyboard to enter a digit. Press Backspace to delete. You can also tap/click the on-screen number buttons.
How do Notes (candidates) work?
Click or press N to toggle Notes mode. Smart Notes can auto-generate and manage candidates, making logical solving much faster.
I'm stuck—what should I do?
Use Hint (shortcut H). Hints point you toward a legitimate next logical step without spoiling the whole puzzle.
Can I undo/redo?
Yes—unlimited undo/redo with Cmd/Ctrl + Z / Y.
Will my progress be saved?
Yes. The game auto-saves. If you close the page or switch devices and come back, you can continue your current board.
How are conflicts/errors indicated?
With Conflict Detection enabled, conflicts are highlighted instantly (e.g., duplicate in a row). A digit counter/tracker also shows usage of digits 1–9.
Is it mobile/tablet friendly?
Yes. The UI is responsive and optimized for touch, with comfortable tap targets on phones and tablets.
Can I create custom puzzles?
Yes. You can start from an empty grid and enter a custom puzzle, with validity checks to prevent impossible or obviously conflicting boards.
Are there keyboard shortcuts?
Common desktop shortcuts: • Arrow keys: move cursor • 1–9: place digit • Backspace: delete • Esc: pause/resume • H: hint • N: toggle Notes • Cmd/Ctrl + Z / Y: undo / redo
Could I lose my progress?
Generally no—progress is auto-saved. Clearing your browser's site data may remove local saves, so do that with care.
How is puzzle quality?
The built-in set is pre-generated and graded for stable quality. Custom puzzles also pass validity checks to reduce no-solution or trivial-conflict cases.
Privacy & open-source license?
This game is based on the open-source project Super Sudoku under the MIT License. If you fork or self-host, please follow the MIT terms.
The page won't load or keys don't work—what can I try?
Refresh the page or use a modern browser (Chrome/Edge/Firefox/Safari). On mobile, if your input method interferes, switch to a numeric keyboard layout.
How do I reset the current board?
Use Clear/Reset to start over. If you want to keep your current progress and begin a new game, open a new tab or export first (depending on your site's implementation).
Why do numbers have different colors?
Colors help you understand the game state: • Black/White: Given clues (cannot be changed) • Teal/Cyan: Numbers you filled in • Yellow/Amber: When you select a cell with a number, all other cells with the same number are highlighted in yellow to help you see the distribution • Red: Conflicting or incorrect numbers (if conflict detection is enabled)
Why do some cells have gray backgrounds?
When you select a cell, the game highlights: • Light gray: All cells in the same row, column, and 3×3 box as your selected cell • Darker gray: All cells containing the same number as your selected cell This helps you quickly identify conflicts and analyze the puzzle logic.
How does Undo/Redo work exactly?
Undo (Ctrl/Cmd+Z) takes you back to your previous action. Redo (Ctrl/Cmd+Y) moves forward if you've undone actions. Important: If you undo and then make a new move, the 'future' history is discarded—just like most text editors.
Why is the Hint button sometimes disabled?
The Hint button is only available when: • You have selected a cell (click on an empty or user-filled cell) • The selected cell is NOT a given clue (black/white numbers) Hints only work on cells you can edit. If you select a given clue or haven't selected any cell, the Hint button will be disabled.
What do the different settings options do?
• Show auto generated notes: Automatically displays all possible candidate numbers in empty cells, updated in real-time based on the current board state. Helpful for beginners to see available options. • Highlight wrong entries: Marks any number that doesn't match the final solution, helping you catch mistakes early without waiting until the end. • Highlight conflicts: Highlights duplicate numbers in the same row, column, or 3×3 box—basic Sudoku rule validation to prevent obvious violations. • Show circle menu when a cell is clicked (desktop only): Shows a visual circular number picker when you click a cell on desktop, providing an alternative to keyboard input. • Show occurrences of numbers in number buttons: Displays how many times each digit (1-9) has been placed on the board, helping you track which numbers still need to be filled in.