Use logic reasoning to fill numbers 1-9 in a 9×9 grid
Difficulty
Easy
Time
00:00
Mistakes
0
Progress
0%
Sudoku Challenge
Use logic to fill numbers 1-9 in the 9×9 grid. Timer starts when you click Start!
🧩 Game Rules
Objective: Fill the 9×9 grid with numbers 1-9 so that each row, column, and 3×3 sub-grid contains all numbers from 1-9.
How to Play:
Click on empty cells to select position
Click number buttons or press keyboard 1-9 keys to input numbers
Press Delete key or click "Clear" to remove numbers
Red numbers indicate conflict errors
Helper Functions:
Hint - Show correct answer for selected cell
Undo - Undo last operation
Check - Check if current input is correct
💡 Sudoku Challenge Tips & Strategy
Sudoku Challenge is the classic 9x9 logic puzzle: fill every row, column, and 3x3 box with the digits 1 through 9 exactly once. No arithmetic, no guessing required - just pure deduction, which is exactly why it is one of the best ways to keep your working memory and pattern recognition sharp. With four difficulty tiers (Easy through Expert), a built-in timer, a mistake counter, and helper tools (Hint, Undo, and Check), you can ease in or jump straight to the deep end. The jump from filling cells to solving fast comes from a handful of scanning techniques that turn a wall of numbers into a clear, step-by-step path.
Tip 1. Scan the fullest rows, columns, and boxes first - regions with the most given digits yield the quickest certain placements.
Tip 2. Find naked singles - any cell with only one possible digit is a free move; sweep for them after every placement.
Tip 3. Use pencil marks on Hard and Expert - tracking candidates per cell reveals hidden singles you would otherwise miss.
Tip 4. Spot hidden singles - if a digit can go in only one cell of a row or box, it must go there, even if the cell has other candidates.
Tip 5. Let red conflicts guide you - the game flags wrong placements in red, so treat every conflict as a free elimination hint.
Play Other Word Games
Explore more fun word games to improve your English skills
Sudoku is played on a 9×9 grid. The goal is to fill the grid so that each row, each column, and each 3×3 box contains the numbers 1-9 exactly once. Some numbers are pre-filled as clues. Use logic to deduce where the remaining numbers belong.
How do I solve Sudoku puzzles?
Start by scanning rows, columns, and boxes for numbers that can only fit in one place. Use the process of elimination. Look for "naked singles" (cells with only one possibility) and "hidden singles" (numbers that can only go in one cell within a unit). Practice these techniques to improve.
What makes a Sudoku puzzle hard or easy?
Difficulty depends on the number and placement of given clues, and the solving techniques required. Easy puzzles have more clues and can be solved with basic logic. Hard puzzles have fewer clues and require advanced techniques like X-Wing, Swordfish, or forcing chains.
Can I use pencil marks (notes)?
Yes! Our Sudoku game supports pencil marks (also called candidates or notes). Click a cell and enter small numbers to track possibilities. This helps you remember which numbers could go in each cell and spot patterns more easily.
Is there only one solution to each puzzle?
A proper Sudoku puzzle has exactly one unique solution. Our game generates puzzles that follow this rule, ensuring fair gameplay. If you reach a contradiction, review your entries - there may be an error in your logic or a mistaken number placement.
