FAQ

✨ Starting your Sudoku journey is very simple:
1. Choose difficulty: Click the 'New Game' button on the homepage and select a challenge from 6 difficulty levels
   • 🟢 Beginner: Suitable for Sudoku newcomers, with more hints
   • 🟡 Easy: Basic difficulty, suitable for players with some experience
   • 🟠 Medium: Moderate challenge, requires more thinking
   • 🔴 Hard: High difficulty, suitable for Sudoku enthusiasts
   • 🟣 Expert: Professional level, challenge your limits
   • ⚫ Extreme: Highest difficulty, only for Sudoku masters
2. Start the game: After selecting the difficulty, the system will automatically generate a new Sudoku puzzle
3. Game interface: Familiarize yourself with the game interface, including the number keyboard, hint function, and timer
💡 Tips: It is recommended that beginners start with the 'Beginner' difficulty and gradually increase the challenge level!

The core rules of Sudoku are very simple and clear:
1. Game board structure: The Sudoku game board is a 9×9 grid, divided into 9 3×3 subgrids (boxes)
2. Number filling rules:
   • ✅ Each row: Numbers 1-9 without repetition
   • ✅ Each column: Numbers 1-9 without repetition
   • ✅ Each 3×3 subgrid: Numbers 1-9 without repetition
3. Game objective: Fill the entire 9×9 grid with numbers 1-9, while satisfying the above three conditions
4. Initial setup: At the start of the game, some cells are pre-filled with numbers as clues, which cannot be changed
5. Automatic checking: The game will real-time check whether your fills are correct and give hints when there are errors
💡 Tip: Start with the row, column, or subgrid with the most hint numbers, which makes it easier to find a breakthrough!

Our game provides an intelligent automatic save function:
1. Automatic save timing:
   • 📱 Automatically save when switching apps or pages
   • ⏸️ Automatically save when pausing the game
   • 🔄 Automatically save after each operation
   • 📴 Automatically save when closing the browser or app
2. Resume game: Next time you enter the game, the homepage will display a 'Continue Game' button, click it to seamlessly resume
3. Multi-device synchronization: After logging in to your account, progress will be automatically synced to the cloud, allowing you to continue playing across different devices
4. Save limit: The system saves progress for up to 10 recent games to ensure reasonable use of storage space
💡 Warm reminder: It is recommended to manually screenshot and backup at important progress nodes, just in case!

Of course! We provide a complete undo function:
1. Undo button location: There is an 'Undo' button (↩️ icon) in the toolbar at the top right corner of the game interface
2. Undo scope:
   • ✅ Can undo recently filled numbers
   • ✅ Can undo note markers
   • ✅ Can undo hint usage
3. Undo times:
   • 🔢 Free users: Up to 10 steps of undo
   • ⭐ Member users: Unlimited undo
4. Keyboard shortcut support:
   • ⌨️ Ctrl+Z (Windows/Linux)
   • ⌘ Command+Z (Mac)
5. Redo function: You can also use the 'Redo' button to restore previous operations after undoing
💡 Tip: When encountering complex situations, skillfully using the undo function can help you avoid dead ends!

Encountering performance issues? Don't worry, try these solutions:
1. Basic troubleshooting steps:
   • 🧹 Clear cache: Browser settings → Clear browsing data → Select 'Cached files and images'
   • 🔄 Update browser: Ensure you are using modern browsers such as Chrome 90+, Firefox 88+, Safari 14+, etc.
   • 📶 Check network: Ensure a stable network, it is recommended to use WiFi or 5G network
2. Advanced optimization solutions:
   • 💻 Close other tabs: Reduce browser memory usage
   • 🔧 Disable browser extensions: Some ad blockers may affect game performance
   • 🎮 Reduce game effects: Turn off animation effects in settings
3. Device-related suggestions:
   • 📱 Mobile users: Restart your phone to ensure sufficient storage space
   • 💻 Computer users: Close unnecessary background programs
4. Emergency contact: If the above methods are ineffective, please contact us through the 'Contact Support' button
💡 Warm reminder: Regularly clearing browser cache can significantly improve game performance!

🔄 Cross-device synchronization function allows you to continue playing anytime, anywhere:
Synchronization prerequisites:
   • 👤 Need to log in to your Sudoku account
   • 🌐 Need a stable network connection
   • 📱 Supports mobile phones, tablets, and computers
Synchronization content:
   • 🎮 Current game progress and status
   • 📊 Game statistics and achievements
   • ⭐ Membership status and privileges
   • 🏆 Battle records and rankings
Synchronization methods:
   • 🔄 Automatic synchronization: Automatically upload to the cloud after each operation
   • 📥 Manual synchronization: Can manually trigger synchronization in settings
   • ⚡ Real-time synchronization: Battle data is synchronized in real-time
Device limit: Supports up to 5 devices logging in simultaneously to ensure data security
💡 Tip: Remember to save the current progress before switching devices to ensure complete data synchronization!

🎁 Become a member and enjoy exclusive privilege feast:
Game experience upgrade:
   • 🚫 Ad-free experience: Pure game environment, focus on Sudoku fun
   • 🔓 Full difficulty unlocked: From beginner to extreme difficulty, challenge at will
   • 🎯 Advanced hint function: Get more precise solving guidance
Data analysis privileges:
   • 📊 Detailed statistics: View detailed data analysis for each game
   • 📈 Progress tracking: Chart showing your skill improvement trajectory
   • 🏆 Achievement system: Unlock exclusive member achievements and badges
Exclusive function privileges:
   • 🆕 Priority experience: First time to experience new functions and game modes
   • 💬 Exclusive community: Join member-only discussion groups and communication platforms
   • 🎨 Personalized customization: Customize game themes and interface styles
Technical support privileges:
   • ⚡ Priority customer service: Enjoy VIP-level technical support services
   • 🔄 Unlimited undo: Unlimited undo operations during the game
   • 💾 Cloud storage: Larger game progress storage space
💡 Member privileges are continuously updated, more surprises await you to discover!

🔄 Detailed steps to cancel membership subscription:
Cancellation path:
   • 📱 Mobile terminal: 'My' page → 'Membership Center' → 'Manage Subscription' → 'Cancel Subscription'
   • 💻 Web terminal: Top right corner avatar → 'Account Settings' → 'Subscription Management' → 'Cancel Subscription'
Cancellation policy:
   • ✅ Effective immediately: No automatic renewal after cancellation
   • ⏳ Privileges retained: Privileges during the paid period continue until the end of the subscription cycle
   • 🔄 Re-subscription: Can re-subscribe at any time to restore all privileges
Refund policy:
   • 💰 Proportional refund: Unused subscription time can be refunded proportionally
   • 📧 Application method: Apply for refund through customer service email
   • ⏰ Processing time: Refund applications are processed within 3-5 working days
Notes:
   • 📋 Please backup important game data before cancellation
   • 💡 Consider pausing the subscription instead of completely canceling
   • 📞 Contact customer service for help if you have any questions
💡 Warm reminder: Before canceling the subscription, it is recommended to experience all privileges for the current cycle!

🧠 Master these techniques and become a Sudoku master:
Basic techniques:
   • 🔍 Unique candidate method: A cell can only be filled with one number
   • 📍 Explicit single: Only one number can be filled in a row/column/box
   • 🎯 Block elimination: Use blocks to limit and eliminate candidates
Intermediate techniques:
   • 🔗 Pair method: Two numbers form a pair in the same row/column/box
   • 🧩 Triple chains method: Special pattern formed by three numbers
   • 🎲 X-Wing technique: Advanced candidate elimination method
Advanced techniques:
   • 🪄 Swordfish technique: Extended version of X-Wing
   • 🌟 Unique rectangle: Using the uniqueness principle to solve problems
   • 🧠 Chain reasoning: Complex logical reasoning chain
💡 It is recommended to start practicing from basic techniques and gradually master advanced techniques!

🌐 Fully compatible, enjoy Sudoku fun anytime, anywhere:
Mobile device support:
   • 📱 iOS: iPhone 8 and above, iOS 14.0+
   • 🤖 Android: Android 8.0+, 2GB RAM and above
   • 📲 Tablet: Perfectly supports iPad and Android tablets
Desktop device support:
   • 💻 Windows: Windows 10/11, Edge/Chrome/Firefox
   • 🍎 Mac: macOS 10.15+, Safari/Chrome/Firefox
   • 🐧 Linux: Mainstream Linux distributions, Chrome/Firefox
Browser requirements:
   • 🌐 Recommended browsers: Chrome 90+, Firefox 88+, Safari 14+
   • 📊 Screen resolution: 1024×768 and above recommended
   • 💾 Storage space: At least 100MB of available space
💡 For the best experience, it is recommended to use the latest version of the browser!

📢 Personalized notification settings, never miss any important information:
Notification types:
   • 🎮 Game reminders: Daily challenges, event start reminders
   • 👥 Social notifications: Friend invitations, battle result notifications
   • 🏆 Achievement notifications: New achievement unlocks, ranking changes
Setting methods:
   • ⚙️ Web terminal: Top right corner settings → Notification management → Custom notification types
   • 📱 Mobile terminal: 'My' page → Settings → Push notifications
Push frequency:
   • 🔕 Do not disturb mode: Can set specific time periods not to receive notifications
   • 📅 Smart push: Intelligently arrange push according to your active time
💡 Reasonably set notifications, can get information in time without causing disturbance!

🎮 Experience exciting Sudoku battles and challenge players worldwide:
Enter battle mode:
   • 🎯 Click the 'Battle' button on the homepage to enter the battle hall
   • 👤 Need to log in to your account to participate in battles
Choose battle method:
   • ⚡ Quick match: System intelligently matches players of similar strength (waiting time 1-3 minutes)
   • 👥 Create room: Customize room name, password, difficulty level, and invite friends to join
   • 🔢 Join room: Enter 6-digit room number to join friends' battles
Battle rules explanation:
   • ⏱️ Time limit: Each battle is limited to 15-30 minutes (customizable)
   • 🎯 Victory determination: The player who completes first with high accuracy wins
   • 📊 Points system: Winning earns points, losing deducts a small amount of points
Battle feature functions:
   • 💬 Real-time chat: Can communicate with opponents during battles
   • 👀 Spectator mode: Friends can watch and learn from masters' techniques
   • 🏆 Leaderboard: View global battle rankings and friend rankings
💡 Battle tips: Start with quick match to familiarize yourself with the battle rhythm, then create rooms to challenge friends!

📊 Scientific ranking system, fairly reflecting your real level:
Core algorithm: Based on the internationally recognized Elo scoring system, widely used in chess game rankings
Scoring factor weights:
   • 🥇 Win/loss result (60%): Defeating higher-ranked players earns more points
   • ⏱️ Completion time (20%): Faster completion earns time bonus points
   • ✅ Accuracy rate (15%): Fewer errors, higher accuracy score
   • 🎯 Difficulty coefficient (5%): High difficulty battles earn extra points
Rank system:
   • 🟢 Bronze: 0-999 points (beginner entry)
   • 🟡 Silver: 1000-1999 points (skilled players)
   • 🟠 Gold: 2000-2999 points (master level)
   • 🔵 Platinum: 3000-3999 points (elite players)
   • 🟣 Diamond: 4000-4999 points (grandmaster level)
   • ⚫ King: 5000+ points (Sudoku god)
Ranking update:
   • 🔄 Real-time update: Ranking is updated immediately after each battle
   • 📈 Season system: Reset the season every 3 months, retain historical highest ranking
   • 🎁 Season rewards: Rewards are distributed based on the rank at the end of the season
💡 Ranking tip: Stable performance is more important than occasional outbreaks, consecutive wins will get a winning streak bonus!