Sudoku Online - Play Free Sudoku Game

What is Sudoku?

Sudoku is a classic number logic puzzle game that originated in Japan and has been popular worldwide for decades. With our online Sudoku web version, you can play Sudoku anytime, anywhere without downloading any software. This Sudoku game perfectly recreates the classic gameplay, features three difficulty levels, and includes an intelligent hint system to help you progress from beginner to expert.

Sudoku Web Version Features

How to Play Sudoku?

Playing Sudoku on our web platform is simple. The Sudoku game uses a 9×9 grid divided into nine 3×3 boxes. The objective is to fill each empty cell with numbers 1-9 so that each row, each column, and each 3×3 box contains all digits from 1 to 9 without repetition.

Basic Rules

  1. Row Rule: Each horizontal row must contain all numbers 1-9, each number appearing only once
  2. Column Rule: Each vertical column must contain all numbers 1-9, each number appearing only once
  3. Box Rule: Each 3×3 box must contain all numbers 1-9, each number appearing only once
  4. Unique Solution: Every Sudoku puzzle has only one solution and doesn't require guessing

How to Play

Sudoku Solving Techniques

1. Naked Singles (Direct Method)

This is the most basic Sudoku solving method. When a cell has only one possible number after analyzing row, column, and box constraints, fill in that number directly. This is the first technique beginners should master.

2. Elimination Method

Observe a particular row, column, or box, and based on existing numbers, eliminate impossible number options. Through progressive elimination, narrow down candidate numbers to find the unique solution.

3. Hidden Singles (Number Position Method)

If a number can only appear in one position within a particular row, column, or box, that number must go in that position. For example, if number 5 can only fit in one cell in a row, fill it there directly.

4. Box-Line Reduction

Observe relationships between 3×3 boxes, using distribution patterns of certain numbers in specific boxes to eliminate possibilities in other regions. This method quickly narrows the solving scope.

5. Naked Pairs

If two cells in the same row/column/box both have only the same two candidate numbers (e.g., both can only be 2 or 7), these two numbers must be distributed in these two cells, so they can be removed from candidate lists of other cells in that row/column/box.

6. Hidden Pairs

If two numbers can only appear in the same two cells within a row/column/box, all other candidate numbers in these two cells can be eliminated. This is an advanced application of the pairs method.

7. Naked Triples

When three cells in the same row/column/box all have the same three candidate numbers, these three numbers must be distributed in these three cells, allowing removal from other cells' candidate lists.

Difficulty Level Explanation

Easy Difficulty

Provides more initial numbers (about 41), with fewer empty cells. Can be completed mainly using naked singles and basic elimination methods, suitable for Sudoku beginners.

Medium Difficulty

Provides moderate initial numbers (about 31), requiring combination of multiple solving techniques. Beyond basic methods, you'll need hidden singles, box-line reduction and other intermediate techniques.

Hard Difficulty

Provides fewer initial numbers (about 21), with many empty cells, requiring advanced techniques and deep logical reasoning. Must master naked pairs, hidden pairs and other advanced techniques, suitable for experienced Sudoku players.

Tips to Improve Your Sudoku Skills

  1. Start Easy: Beginners should start with easy difficulty to master basic solving techniques first
  2. Use Notes Wisely: Marking candidate numbers is very important for discovering hidden patterns
  3. Think Systematically: Don't guess blindly - every Sudoku step should be based on logical reasoning
  4. Practice Often: Improve speed and accuracy through extensive practice with various puzzle types
  5. Learn Techniques: Gradually learn and master various advanced solving techniques to expand problem-solving approaches
  6. Review Games: After completing puzzles, review the solving process to summarize experiences and lessons
  7. Be Patient: Sudoku requires high concentration and patience; rushing leads to mistakes

Benefits of Playing Sudoku

Why Choose Our Online Sudoku?

Compared to Sudoku apps that require downloading, our Sudoku web version offers instant play advantages. It doesn't occupy your device storage space and can be played anytime through your browser. Our Sudoku online platform is carefully optimized to ensure smooth operation on all devices. Whether you're a Sudoku beginner or expert player, you'll find challenges suited to your skill level here.

Frequently Asked Questions

Q: Does Sudoku need to be downloaded?

A: No! Our Sudoku web version requires no download - just open your browser and play.

Q: Does it work on mobile?

A: Absolutely! Works smoothly on phones, tablets, and computers with responsive design that adapts to your screen.

Q: How do I use the hint feature?

A: Click the "Hint" button and the system will randomly select an empty cell and fill in the correct answer.

Q: What's notes mode for?

A: Notes mode lets you mark multiple candidate numbers (small digits 1-9) in cells to help with logical reasoning, especially useful for difficult puzzles.

Q: Is there a limit on mistakes?

A: Yes, to add challenge, the game ends after 3 mistakes and you'll need to start over.

Q: Can I undo moves?

A: Yes! Click the "Undo" button to undo your last move and correct mistakes.

Q: Does every Sudoku puzzle have a unique solution?

A: Yes, every puzzle we generate is guaranteed to have one and only one solution - no guessing required.

Ready for the Challenge?

Choose your difficulty and start your Sudoku journey!

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