How Can We Help?

Do I need to create an account?

No account is required. Classic Sudoku Master is completely free to play without signing in. Your progress and statistics are saved locally on your device.

Is the app free?

Yes, the app is free to download and play. It is supported by ads. There are no in-app purchases.

Which devices are supported?

Classic Sudoku Master is available on iOS (iPhone and iPad) and Android devices. It requires iOS 14 or later, or Android 8.0 or later.

How do I use hints?

Tap the lightbulb icon during a game to reveal a hint. Hints are limited per game — use them wisely when you're truly stuck.

What difficulty levels are available?

The app offers four difficulty levels: Easy, Medium, Hard, and Expert. Each level adjusts the number of pre-filled cells and the complexity of the logic required to solve the puzzle.

Can I undo a move?

Yes. Tap the undo button (curved arrow icon) to revert your last move. You can undo multiple times to step back through your moves.

What does the notes/pencil mode do?

Notes mode lets you write candidate numbers in a cell without committing to them. This is useful for advanced solving techniques. Tap the pencil icon to toggle notes mode on or off.

Can I pause a game and come back later?

Yes. Your game is automatically saved when you close the app. Simply reopen the app and continue where you left off.

Where is my game data stored?

All your game progress, statistics, and settings are stored locally on your device. We do not store your game data on any server.

Will I lose my progress if I reinstall the app?

Yes. Because data is stored locally, uninstalling the app will erase your saved progress and statistics. We recommend completing your current game before reinstalling.

How is my best time calculated?

Your best time is the fastest time you have completed a puzzle at each difficulty level. The timer starts when the puzzle loads and stops when you correctly fill all cells.

Why does the app show ads?

Ads allow us to keep Classic Sudoku Master free for everyone. We use Google AdMob to display ads and apply cooldown periods between ads to keep the experience enjoyable.

How do I opt out of personalised ads?

On iOS, go to Settings → Privacy & Security → Tracking and disable tracking for Classic Sudoku Master.

On Android, go to Settings → Google → Ads → Delete advertising ID or Opt out of Ads Personalisation.

What data does the app collect?

We collect anonymous usage analytics, crash reports, and ad identifiers (with your consent on iOS). We do not collect your name, email, location, or any other personal information. Read our full Privacy Policy for details.

The app crashes or freezes. What should I do?

Try the following steps in order:

• Force-close the app and reopen it.
• Restart your device.
• Check for an app update in the App Store or Google Play.
• If the issue persists, contact us with your device model and OS version.

Ads are not loading. Is that normal?

Ads may occasionally fail to load due to network conditions or ad inventory availability. This is normal and does not affect gameplay. Check your internet connection if ads consistently fail to appear.

The app is not available in my country. Why?

Classic Sudoku Master is available in most countries. If you cannot find it, it may be due to regional store restrictions. Contact us and we will look into it.