1ClickGamesSudoku
Play free online Sudoku 9x9 number puzzles. Complete the grid so every row, column, and 3x3 box contains numbers 1 through 9 with instant free play.
📖 How to Play & Game Overview
Fill the 9x9 grid so every row, column, and 3x3 subgrid contains all digits from 1 to 9 without repeating any number. Use logic, scanning, and pencil notes to solve each puzzle.
Core Game Rules:
- Each row must contain the numbers 1 through 9 without repetition.
- Each column must contain the numbers 1 through 9 without repetition.
- Each 3x3 box (9 total boxes) must contain the numbers 1 through 9 exactly once.
- Starting pre-filled digits (givens) are fixed and cannot be changed or moved.
- Every valid Sudoku puzzle has exactly one unique mathematical solution.
Winning Strategies & Tips:
- Naked Singles: Find cells where only one possible number can mathematically fit based on existing row, column, and box numbers.
- Hidden Singles: If a number can only be placed in one specific cell within an entire row, column, or 3x3 box, place it immediately even if other candidate notes exist.
- Cross-Hatching / Scanning: Scan two parallel rows or columns that already contain a digit to immediately pinpoint its location in the third 3x3 box.
- Use Pencil / Notes Mode: Toggle Notes (press N) on Hard and Expert difficulties to track candidate numbers in open cells.
- Locked Candidates / Line-Box Reduction: When a candidate digit is restricted to a single row or column within a 3x3 box, eliminate that digit from the rest of that row or column.
Keyboard Controls
- Place number in selected cell 1-9
- Navigate grid cells Arrow Keys
- Toggle Pencil/Notes candidate mode N
- Clear selected cell Backspace / Del
❓ Frequently Asked Questions
Can all Sudoku puzzles be solved without guessing?
Yes! Every properly designed Sudoku puzzle on 1ClickGames has a unique solution that can be deduced purely through logic, scanning, and candidate elimination without ever needing to guess.
What is the best way for beginners to start solving Sudoku?
Beginners should start by scanning for the most frequently occurring numbers on the board (digits that appear 5 or 6 times) and cross-hatch rows and columns to fill the remaining instances easily.
How do Pencil Notes work in online Sudoku?
Press "N" or tap the Pencil Notes button to switch from placing final numbers to jotting down small candidate numbers. When you place a confirmed digit, conflicting pencil notes in the same row, column, and box are updated.
What is the difference between Easy, Medium, Hard, and Expert Sudoku?
Easy puzzles provide 36-40 starting clues requiring basic single-scanning. Medium puzzles require hidden singles and pair elimination. Hard and Expert puzzles provide fewer clues and require advanced techniques like X-Wings, Swordfish, and Box-Line reductions.
🏆 Local High Scores
| Rank | Score | Date |
|---|---|---|
| No scores recorded yet | ||
⚡ Game Features
- ✓ 100% Free & Unlimited Play
- ✓ Instant Browser Play (No Download)
- ✓ No Account Required (Instant Play)
- ✓ Responsive Touch & Keyboard Controls
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