🎯 Game Objective

Sudoku is a logic-based number puzzle where you must fill a 9×9 grid with digits 1-9. Each row, column, and 3×3 subgrid (called a "box" or "region") must contain all digits from 1 to 9 exactly once. The puzzle starts with some numbers already filled in, and you must use logic to determine the rest.

📋 Basic Rules

🔢 Numbers 1-9

Only use digits 1 through 9. No letters, symbols, or other numbers allowed.

📏 Row Constraint

Each horizontal row must contain all digits 1-9 exactly once.

📐 Column Constraint

Each vertical column must contain all digits 1-9 exactly once.

📦 Box Constraint

Each 3×3 subgrid must contain all digits 1-9 exactly once.

🧠 Basic Solving Techniques

1️⃣ Naked Singles

What it is: A cell where only one number can fit based on the constraints.

How to find: Look for empty cells where 8 out of 9 numbers are already present in the same row, column, or box.

Example: If a row has numbers 1,2,3,4,5,6,7,8 and one empty cell, that cell must be 9.

2️⃣ Hidden Singles

What it is: A number that can only go in one specific cell within a row, column, or box.

How to find: For each missing number, check where it can be placed in each row, column, and box.

Example: If the number 7 can only fit in one cell within a 3×3 box, place it there.

3️⃣ Pencil Marks

What it is: Writing small candidate numbers in cells to track possibilities.

How to use: In each empty cell, write all numbers that could potentially go there.

Tip: Update pencil marks as you fill in numbers to maintain accuracy.

🎓 Intermediate Techniques

🎯 Pointing Pairs/Triples

When a candidate number in a box can only appear in one row or column, eliminate that number from the same row/column outside the box.

📦 Box/Line Reduction

If a number in a row/column can only fit within one box, eliminate that number from other cells in the same box.

👥 Naked Pairs

When two cells in the same unit contain the same two candidates, eliminate those numbers from other cells in the unit.

🕵️ Hidden Pairs

When two numbers can only appear in two specific cells within a unit, eliminate all other candidates from those cells.

🚀 Advanced Strategies

⚔️ X-Wing

A pattern where a candidate appears in only two positions in two different rows/columns, forming a rectangle. Eliminates candidates from intersecting lines.

🐟 Swordfish

Extension of X-Wing using three rows and three columns. More complex but follows similar elimination principles.

🔗 Simple Coloring

Using two colors to mark strongly linked candidates, helping identify contradictions and eliminations.

🌐 Forcing Chains

Following logical chains of implications to find contradictions or forced placements.

📝 Step-by-Step Solving Process

Scan for Naked Singles: Look for cells with only one possible number.
Check for Hidden Singles: Find numbers that can only go in one place.
Fill in Obvious Numbers: Complete any cells you can determine immediately.
Add Pencil Marks: Write candidate numbers in remaining empty cells.
Apply Intermediate Techniques: Use pointing pairs, naked pairs, etc.
Update Pencil Marks: Remove eliminated candidates after each placement.
Repeat Process: Continue cycling through techniques until solved.
Use Advanced Methods: Apply complex strategies if needed for difficult puzzles.

💡 Pro Tips

Start with constraints: Focus on rows, columns, and boxes with the most numbers filled.
Look for patterns: Scan for obvious placements before diving into complex techniques.
Keep pencil marks clean: Regularly update and clean your candidate notes.
Work systematically: Don't jump around randomly; follow a logical sequence.
Double-check placements: Verify each number doesn't violate any constraints.
Take breaks: Step away if you're stuck; fresh eyes often spot new possibilities.
Practice regularly: Consistent practice improves pattern recognition and speed.
Learn from mistakes: Analyze errors to understand where your logic went wrong.

🚫 Common Mistakes

❌ Guessing

Never guess! Every Sudoku has a unique solution that can be found through logic alone.

❌ Ignoring Constraints

Always check all three constraints (row, column, box) before placing a number.

❌ Messy Pencil Marks

Keep candidate notes organized and updated to avoid confusion and errors.

❌ Rushing

Take your time to think through each placement. Speed comes with practice and experience.

📊 Difficulty Levels

🟢 Easy

Solvable using only naked singles and hidden singles. Great for beginners to learn basic logic.

🟡 Medium

Requires basic elimination techniques like pointing pairs and simple intersections.

🟠 Hard

Needs intermediate techniques such as naked/hidden pairs and box/line reductions.

🔴 Expert

Demands advanced strategies like X-Wing, Swordfish, and complex elimination patterns.

⚫ Master

Requires the most sophisticated techniques including forcing chains and advanced coloring.

🏃‍♂️ Speed Solving Tips

👁️ Pattern Recognition

Train your eyes to quickly spot common patterns and number placements.

🔄 Technique Order

Develop a consistent order for applying techniques to avoid missing opportunities.

⚡ Quick Scanning

Practice rapid visual scanning to identify naked and hidden singles faster.

🧠 Mental Notes

For easier puzzles, try to solve without pencil marks to improve mental calculation.

🎯 Practice Recommendations

🌱 Beginner (Week 1-2)

Solve 2-3 easy puzzles daily
Focus on naked and hidden singles
Practice using pencil marks
Learn to scan systematically

🌿 Intermediate (Week 3-6)

Solve 1-2 medium puzzles daily
Learn pointing pairs and box/line reduction
Practice naked and hidden pairs
Work on speed and accuracy

🌳 Advanced (Month 2+)

Tackle hard and expert puzzles
Master X-Wing and Swordfish
Learn coloring techniques
Challenge yourself with time limits

🎮 Ready to Solve?

Now that you understand the techniques and strategies, it's time to put your Sudoku skills to the test!

Play Sudoku Game