Privacy Policy

Effective date: July 29, 2026

Detlev Voss ("we", "us", "our") operates the Sudoku mobile application (the "App"). This page informs you about our policies regarding the collection, use, and disclosure of personal data when you use the App.

1. Data We Collect

1.1 In-Progress Puzzle, Preferences, and Games-Played Count

The App stores the following information on your device:

In-progress puzzle: the puzzle you are currently playing, so you can resume it after closing the App.
User preferences: your appearance choice, difficulty, and other in-app settings.
Games-played count: a single number counting how many games you have completed. The App uses it only to decide when to show an optional prompt — for example, to offer a tip or to invite an App Store review. It is not linked to anything that identifies you and is used purely inside the App; it is never transmitted to us or to any third party.

1.2 Game Statistics

When statistics collection is enabled (the “Collect statistics” setting, on by default), the App keeps one record per game you play so it can show your progress on the Statistics screen. Each record contains only gameplay facts — never anything that identifies you:

the difficulty, and whether Challenge Mode was on;
when the game started and ended, and how long you actively spent on it;
how many hints, reveals, and incorrect entries you made;
the solving techniques the puzzle required, and the result (solved, lost, or abandoned).

These records are stored on your device using Apple's SwiftData and are aggregated into the figures shown in the App (games solved, win rate, best and median times, and a per-difficulty breakdown). You can turn recording off at any time with “Collect statistics”, and remove everything already recorded with “Delete statistics data”, both in the App's settings. Turning collection off does not delete existing records; use “Delete statistics data” for that.

1.3 Optional iCloud Sync via CloudKit

Data can be kept in step across your Apple devices through your private iCloud database using Apple's CloudKit:

Preferences and games-played count sync only when you turn on “Sync settings via iCloud” in the App's settings. This is opt-in and off by default.
Game statistics are stored in your private iCloud database and sync automatically whenever you are signed in to iCloud with iCloud Drive enabled for the App. They stop syncing if you sign out of iCloud or disable iCloud for the App, and you can remove them with “Delete statistics data”.

Your in-progress puzzle is stored locally on each device and does not sync — every device resumes the game it last saved. All of this data lives in your own iCloud account; we have no access to it. If you are not signed in to iCloud, or if iCloud is unavailable, the App automatically falls back to local-only storage and remains fully usable offline.

1.4 Local Settings on Your Device

Some settings are stored locally on your device using Apple's UserDefaults mechanism. This includes a randomly generated identifier that lets the App tell your own devices apart when syncing preferences. This identifier is created on your device, is not linked to your name or any account, and is never used to track you. This data never leaves your device except through Apple's standard device backup features.

1.5 Tip Jar (Optional In-App Purchases)

The App offers an optional tip jar with one-time in-app purchases as a way to support development. Tipping is entirely voluntary and the App is fully usable without it. Purchases are processed by Apple through the App Store — we never see or receive your payment details, such as your card number or billing address. So that the App does not ask again once you have tipped, it reads your tip purchase history from the App Store on your device; this information stays on your device and is not sent to us.

2. Data We Do Not Collect

We do not collect personal information such as your name, email address, or account credentials.
We do not receive your game statistics. The per-game records described in section 1.2 stay on your device and in your own private iCloud; they are never transmitted to us or shared with any third party, and contain no information that identifies you.
We do not operate any server that receives your data. All App data lives either on your device or in your own private iCloud storage.
We do not use analytics, crash reporting, or advertising frameworks.
We do not track you across other apps or websites.
We do not share any data with third parties.
We do not use cookies or similar tracking technologies.
An internet connection is only required if you choose to use iCloud sync; the App is fully playable offline.

3. Third-Party Services

The App does not integrate any third-party services, SDKs, or analytics tools. It relies only on Apple platform services: SwiftData for on-device storage, CloudKit (your private iCloud database) for device-to-device synchronisation, and StoreKit / the Apple App Store to process the optional tip-jar purchases. The App is distributed exclusively through the Apple App Store, which is operated by Apple Inc. and subject to Apple's own privacy policy.

4. Data Storage and Security

All data created by the App (in-progress puzzle, preferences, games-played count, and game statistics) is stored locally on your device. Your game statistics are also stored in your private iCloud database when you are signed in to iCloud, and your preferences and games-played count are stored there too if you have enabled “Sync settings via iCloud”. Your private iCloud database is managed and protected by Apple. We never receive or access this data.

5. Children's Privacy

The App does not knowingly collect personal information from children. Since the App does not transmit any personal data to us, it is safe for users of all ages.

6. Your Rights Under GDPR

Since all App data is stored exclusively on your device and, optionally, in your own private iCloud account, and we have no access to it, the following applies:

Right of access: All your data is visible within the App at all times.
Right to erasure: You can erase your game statistics at any time inside the App with “Delete statistics data”, and stop new records with “Collect statistics”. You can remove all App data, including the games-played count, by deleting the App from your device. Synced data can additionally be removed via the iOS Settings under “iCloud → Manage Storage”.
Right to data portability: App data is included in your standard device backups and, if enabled, in your iCloud backup.
Right to object: You can disable optional iCloud sync at any time in the App, and manage the App's permissions at any time in your device's Settings.

7. Changes to This Policy

We may update this Privacy Policy from time to time. Changes will be posted on this page with an updated effective date. We encourage you to review this page periodically.

8. Contact

If you have questions about this Privacy Policy, please contact us at:
support@advoss.de