Privacy Policy
Last updated: September 29, 2026
- Sudoku is an online game. When you first open it, it creates an anonymous guest account for you. No name, email or sign-up is needed to play.
- Your player name, scores, battle rating and online status are visible to other players on leaderboards, in battles and in friend lists.
- You can optionally link Apple, Google or an email address to keep your progress across devices.
- The game has no ads and no in-app purchases. We do not sell your data or use it to track you across other apps.
- You can delete your account and its data at any time from Settings → Delete account.
This policy explains what information the Sudoku mobile app by Hangar Apps ("Sudoku", "the app", "the game") handles on iOS and Android, why, and what choices you have. Sudoku is published by Hangar Apps ("we", "us"). If you have a question, contact us at [email protected].
1. Information we store on our servers
Sudoku uses Google Firebase as its backend. The following is stored there and linked to your account:
- Account identifier: a random user ID created automatically on first launch. It is not linked to your name or email unless you choose to link a sign-in method.
- Sign-in details (optional): if you link Apple, Google or email, Firebase Authentication stores your email address and the identifier of that sign-in provider. With Sign in with Apple you may hide your real email. Email passwords are stored by Firebase in hashed form; we cannot see them.
- Player profile: the player name you choose (or an automatic one such as "Solver-AB12"), your friend code, level, experience points, streaks, battle rating, wins and losses, and the time you were last active in the app.
- Game results: for each finished game, the puzzle, difficulty, start and finish time, duration, number of mistakes and hints, your final board and score. The moves you made are sent once so the server can verify the result; they are not kept afterwards.
- Progress: statistics, achievements, daily tasks and daily challenge results.
- Friends and invitations: your friend list, friend requests you sent or received, battle invitations and head-to-head scores.
- Battle matches: the players, their progress and mistakes, the result and the rating change of each online match.
- Notification device record (optional): if you turn on notifications, a push token, your platform (iOS or Android), a random installation ID and your reminder preference.
2. Information other players can see
Because Sudoku is a competitive online game, some information is public to other signed-in players:
- your player name, friend code and battle rating
- your leaderboard and daily challenge entries: score, time, mistakes, hints used and difficulty
- your battle wins and losses, and your live progress to your opponent during a match
- whether you are currently online, shown to your friends
Please do not use your real full name or other personal details as your player name. Your email address is never shown to other players.
3. Information stored only on your device
- the game in progress, including your notes, and your local game history
- gameplay settings such as haptics, highlighting and the mistake limit
- a copy of the daily challenge and results waiting to be sent, so you can play offline
Uninstalling the app removes this data. If you use your device's own backup (for example iCloud Backup or Google backup), that backup may include it.
4. Information handled by third-party services
| Service | What it's for | Data it may collect |
|---|---|---|
| Firebase Authentication | Guest accounts and optional Apple, Google or email sign-in | User ID, email address and provider identifier if linked, IP address, device information |
| Cloud Firestore and Cloud Functions | Storing and validating the game data described in sections 1 and 2 | The data listed above, IP address |
| Firebase App Check (Apple App Attest / DeviceCheck, Google Play Integrity) | Checking that requests come from a genuine copy of the app, to prevent cheating and abuse | Device and app integrity signals |
| Google Analytics for Firebase | Understanding how the game is used, for example how many games are started and finished | Your user ID, app instance ID, game events (such as game started or completed, difficulty, battle result), device model, OS version, language, country derived from IP address. On iOS the advertising identifier (IDFA) is not collected. On Android, Google Analytics may collect the Android advertising ID. |
| Firebase Crashlytics | Finding and fixing crashes and errors | Your user ID, crash and error details, device model, OS version, app version |
| Firebase Cloud Messaging | Sending push notifications, only if you turn them on | Push token, device information |
| Firebase Remote Config | Loading game settings such as feature switches | App instance ID, device and app information |
| Sign in with Apple / Google Sign-In | Signing you in, only if you choose one of them | Handled by Apple or Google under their own policies. We receive a sign-in token and your email address. |
Privacy policies of these providers: Google · Firebase · Apple
This website is hosted by Cloudflare, which receives your IP address and browser information to deliver the page, like any website host.
5. Ads, purchases and tracking
Sudoku currently shows no ads and has no in-app purchases or subscriptions. We do not sell your personal information, and we do not track you across apps and websites owned by other companies. If this changes, we will update this policy before that version is released.
6. Device features and permissions
- Notifications (optional): notifications are off until you turn them on in Settings. If you do, the game can notify you about the daily challenge, your streak, friend requests and battle invitations. You can turn them off in the app or in your device settings.
- Internet: needed for leaderboards, battles, friends and syncing. Classic games and a downloaded daily challenge can be played offline.
- Sharing and clipboard: when you tap Share or Copy, your friend code or invite link is passed to the app you choose. The game does not read your clipboard.
- Sudoku does not use your location, contacts, camera, microphone or photos.
7. Fair play checks
To keep leaderboards fair, every result is checked on our servers before it is ranked. This check is automated and looks at the game itself, for example whether the solution is correct and whether the solving time is realistic. A rejected result is not ranked. If you think a result was rejected by mistake, contact us.
8. Why we process data (legal bases)
Where the EU/UK GDPR or Turkey's Personal Data Protection Law No. 6698 (KVKK) applies, we rely on:
- Performing our contract with you to provide the game, your account, leaderboards, friends and battles.
- Our legitimate interest in keeping the game secure and fair, fixing errors, understanding how the game is used and answering your emails.
- Your consent for push notifications. You can withdraw it at any time.
9. Deleting your account and retention
You can delete your account in the app from Settings → Delete account. This works for guest accounts too. It permanently removes your profile, friend code, statistics, game results, achievements, friend list, notification device records, leaderboard and daily challenge entries, and your sign-in details. It cannot be undone. If you cannot use the app, email [email protected] from the address linked to your account, or include your friend code, and we will delete it for you.
- Account data is kept until you delete your account.
- Battle match records are deleted automatically about 30 days after the match.
- Records shared with another player, such as friend requests and battle invitations that include the player name you had at the time, may remain after deletion. Email us if you want them removed.
- Analytics and crash data is kept by Google for a limited period under its retention settings, and then deleted or anonymized.
- Signing out does not delete your account. If you email us, we keep the conversation only as long as needed to help you.
10. International transfers
Our servers run on Google Cloud. Google and its sub-processors may process data in the European Union, the United States and other countries. Where required, they use recognized safeguards such as the European Commission's Standard Contractual Clauses.
11. Children
Sudoku is a general-audience game and is not directed at children under 13, or under the minimum age required in your country. We do not knowingly collect personal information from children. If you believe a child has provided personal information through the game, please contact us and we will remove it.
12. Your rights
Depending on where you live (for example under GDPR, KVKK, or California's CCPA/CPRA), you may have the right to access, correct, delete, or receive a copy of your personal data, to object to or restrict processing, and to withdraw consent. You can change your player name and delete your account in the app. For anything else, email us at [email protected]. We do not sell your personal information. You also have the right to complain to your local data protection authority.
13. Security
Data is sent over encrypted connections. Scores, ratings and other competitive data can only be written by our servers, and each player can only read their own private data. No system is perfectly secure, so we cannot guarantee absolute security.
14. Changes to this policy
If Sudoku starts handling data differently, for example by adding ads or purchases, we will update this policy before that version is released. The "Last updated" date at the top always shows the latest version, and important changes will be announced in the app or in the store release notes.
15. Contact
Hangar Apps
Email: [email protected]