Privacy Policy

Last updated: September 17, 2026  ·  Applies to: Sudoku Cube (Android)

1. Who We Are

Sudoku Cube is developed and published by virt-services ("we", "us", "our"). If you have any questions about this policy, contact us at support@virt-services.com.

2. Data Stored on Your Device

The app stores the following data on your device only:

• Your puzzle progress, solved puzzles, saved games and game statistics
• Your settings and preferences (theme, language, text size, etc.)
• Hint usage and Daily Cube completion records
• Ad pacing counters (how many puzzles since the last full-screen ad, and the timer that opens the next free game when you choose not to watch an ad)

This data leaves your device only if you use the optional Google Play Games backup described in section 7. Nothing else reads it.

3. Advertising — Google AdMob

Sudoku Cube is free and funded by ads. There are no purchases. Ads are provided by Google AdMob (Google LLC), which may collect and use data to serve personalised or non-personalised ads, depending on your consent choice.

According to Google's own disclosure for its ads SDK, AdMob may collect:

• Your IP address, which may be used to estimate the device's general location
• Product interactions — app launch, taps and video views on ads
• Diagnostic information about the app's and the SDK's performance
• Device and account identifiers — the Android advertising ID (resettable in Android Settings), the app set ID and, where applicable, identifiers related to accounts signed in on the device

Your consent. Before showing ads to players in the EEA, the UK and Switzerland, the app presents Google's consent dialog (User Messaging Platform). You can change your choice at any time in Settings → Account → Privacy Settings; that row is shown when your region requires a choice. Elsewhere, you can reset or opt out of the advertising ID in Android: Settings → Privacy → Ads. If you decline personalised ads you still see ads, but they are not tailored to your interests.

What kind of ads. The app asks AdMob for ads rated Teen or lower and never for mature content. In our AdMob settings we additionally block these categories: politics, references to sex, religion, dating, gambling and betting, social casino games, get-rich-quick schemes, weight loss, and cosmetic procedures.

Unity Ads, through AdMob. The app includes Google's adapter for Unity Ads (Unity Technologies), which AdMob can use to fill an ad request. The Unity Ads SDK starts with AdMob's and may collect the Android advertising ID, your IP address (and the approximate location derived from it), device and app information, and your interactions with its ads. Your consent choice above is passed to Unity through Google's consent framework. Unity's privacy policy: unity.com/legal/game-player-and-app-user-privacy-policy.

For full details, see Google's Privacy Policy: policies.google.com/privacy.

4. Analytics, Crash Reports and Remote Settings — Google Firebase

We use three Firebase services from Google. None of them receives your name, email address, or the content of your puzzles.

Analytics (Google Analytics for Firebase). Off by default. It is switched on only when your ad-consent choice allows it — the same choice as in section 3 — and can be switched off again there at any time. What we record is in-app behaviour: which screens and modes are opened, puzzle completions, notification interactions, and advertising events, including the estimated value of each ad impression as reported by the ads SDK. We do not use it to build a profile of you.

Crash reports (Firebase Crashlytics). When the app crashes, a report is sent so that we can fix the crash: the stack trace, the app's state at the time, device metadata (model, OS version, free memory) and a Crashlytics installation identifier used to count how many installations a crash affects. Crash reporting is on by default and is not tied to the ads choice, because a crash we cannot see is a crash we cannot fix. It is switched off on emulators.

Remote settings (Firebase Remote Config). The app fetches a handful of settings (ad pacing, when the "update available" card and banner may appear, how long the new-message banner stays, and whether messages are fetched) from Google. The request carries your country code, language, time zone, OS version and the app's identifier — no personal data.

Firebase installation ID. All three services use a per-installation identifier that Firebase creates on first launch. Google states it does not uniquely identify a user or a physical device; it is discarded when you uninstall.

Firebase privacy and security: firebase.google.com/support/privacy.

5. Purchases — None

Sudoku Cube is free and offers nothing to buy. Google's billing library is present in the app for technical reasons, but no product exists and no purchase can be made, so no payment or purchase data is collected.

6. Daily Puzzles

The Daily Cube downloads one pre-generated puzzle file per day from this site, at https://sudoku-cube.virt-services.com/daily/<date>.json. The request is an ordinary anonymous HTTP GET for a static file. It includes your IP address as a standard part of any HTTP connection. No personal identifiers, no device identifier, and no game data are sent, and no request logs are retained beyond the hosting provider's standard operational logs.

Once downloaded, the puzzle is cached on your device so it can be replayed offline. If the file cannot be reached, the app generates the day's puzzle locally instead — the Daily Cube keeps working with no network at all.

6a. Daily Leaderboard — not yet active

This feature is not live. No leaderboard server is currently running, no solve data leaves your device today, and the app treats the leaderboard as unavailable. This section describes what would happen if and when we turn it on, so the disclosure is in place before any data is ever sent.

When active, finishing a Daily Cube would submit to https://sudoku-cube.virt-services.com/api/leaderboard:

• A random identifier generated on your device the first time you complete a daily. It is not linked to your name, email, Google account, or advertising ID, and it is not shared with any third party.
• The puzzle date, your solve time, and your move count.

Nothing else. Clearing app data or uninstalling the app discards the identifier permanently. We will update this page and the Google Play Data safety form before the leaderboard is enabled.

6b. Messages from the Sudoku Cube team

The app downloads the team's messages — news about releases, events and new modes — as one signed static file from this site, https://sudoku-cube.virt-services.com/messages/index.json, after it starts and when you return to it. The request is an ordinary anonymous HTTP GET, like the daily puzzle: it includes your IP address as a standard part of any HTTP connection, and no personal identifier, device identifier or game data. The messages are kept on your device so they can be read offline, and which ones you have read is recorded on your device only.

If analytics is allowed (section 4), the app records that a message was received, opened or read, with the message's id, the language it was shown in and where it was opened from (the banner, a notification or the inbox).

7. Progress Backup — Google Play Games (optional)

Your progress can survive a lost phone or a factory reset: the app backs it up to your own Google account, through Google Play Games Services.

• Sign-in is Google's own automatic Play Games sign-in, with Google's prompt. There is no account of ours. Without Play Games, nothing is backed up.
• The app reads your Play Games player ID — a Google identifier for you in Play Games — and your Play Games name. The name is shown on the home screen of this phone only: the app does not store it, does not put it in the backup and does not send it anywhere. Nothing else is read from your account: not your email, not your contacts.
• Your progress (section 2, minus device-only settings such as notification toggles) is saved, compressed, into your Google account's Play Games saved-games storage — automatically after a puzzle and when you leave the app, or when you tap Back up now — and brought back when you tap Restore. It never passes through a server of ours.
• Settings → Account lets you turn automatic backup off, and Disconnect stops the app from using Play Games on this phone until you connect again.
• To delete the backup, use Google's controls: the Google Play Games app → Settings → delete Play Games data for this game, or your Google account's data controls. Uninstalling the app does not delete the backup, so that a reinstall can restore it.

8. Notifications

The app can send you four kinds of notifications, each controlled by its own toggle in Settings → Notifications. On a new install, New daily puzzle, Announcements and Events are on and Daily reminder is off. On Android 13 and later nothing is shown until you grant the notification permission, which the app asks for the first time you open the Events tab or turn a toggle on — never at launch.

Daily reminder and New daily puzzle (local). Notifications scheduled by your device — a reminder at a time you choose, and a note when a new Daily Cube is available. The schedules are stored on your device only — no network calls, no identifiers leave the device.

Announcements and Events (remote, via Firebase Cloud Messaging). While a toggle is on, the device is subscribed to the corresponding FCM topic on Google's infrastructure: events, and for announcements the topic of your app language (for example announcements-fr), so that a message reaches you in that language. Subscription is topic-based, not token-based:

• A device-scoped FCM token is generated by Google for delivery routing, but the app never reads, persists, or transmits this token. We do not store it anywhere. We do not operate a server that maps tokens to users.
• We do not know which specific devices subscribe — we send a push to a topic name and Google's FCM service fans it out to all currently subscribed devices.
• Notification taps open a named screen in the app (home, mode selection, the achievement hub, the Daily Cube, What's New, or a message from the team). The screen name and the message id are in the notification payload; no per-user data is.

You can turn any toggle off at any time. Disabling Announcements or Events unsubscribes the device from its topic; disabling a local notification cancels its schedule.

Data that Firebase Cloud Messaging processes while a topic toggle is on:

• Device-scoped FCM token (held by Google, not by us)
• Topic membership (announcements-<language>, events) and the app's version at subscription time
• IP address as a standard part of any FCM connection

9. Permissions

The app requests only the permissions required to function:

• Internet access — to load daily puzzles and the team's messages, display ads, fetch remote settings, send crash reports, back up with Google Play Games, and receive FCM notifications
• Network state — to check connectivity before making requests
• Post notifications (Android 13+) — requested the first time you open the Events tab or turn a notification toggle on; not requested at app launch. Without this permission the OS will not display any notification regardless of toggle state.

No access to your camera, microphone, contacts, location, or files is requested.

10. Children

Sudoku Cube is intended for players aged 16 and over and is not directed at children. We do not knowingly collect personal information from children. If you believe a child has provided personal information through the app, please contact us so we can take appropriate action.

11. Your Rights

Wherever you are, you can:

• Change or withdraw your ad-personalisation consent (Settings → Account → Privacy Settings, where your region requires a choice) or reset your advertising ID in Android settings
• Switch off any notification toggle (Settings → Notifications) — disabling Announcements or Events unsubscribes the device from the corresponding topic on Google's side
• Delete everything the app holds on your device by uninstalling it
• Stop the Play Games backup on this phone (Settings → Account → Disconnect, or turn automatic backup off) and delete the backup through Google's controls (section 7)

If you are located in the European Economic Area or the United Kingdom, you also have the rights the GDPR / UK GDPR give you, including the right to lodge a complaint with your local data protection authority. We hold no personal data on servers of our own, so a deletion request to us has nothing to act on; the identifiers described above are held by Google and can be reset or deleted through the controls named in this policy.

12. Data Retention

Game data stays on your device until you uninstall the app. We do not maintain servers that store personal data. Crash reports, analytics events and advertising data are retained by Google under Google's retention policies. Topic-based FCM subscriptions end when you disable the toggle or uninstall. A Play Games backup stays in your Google account until you delete it.

13. Changes to This Policy

We update this page when the app adds a feature that touches data, and the "Last updated" date at the top of this page changes with it. Significant changes are also noted in the app's update notes. Continued use of the app after an update constitutes acceptance of the revised policy.

14. Contact

For any privacy-related questions or requests, please contact:

virt-services
support@virt-services.com