Privacy Policy

Muzukashii (“the app”) is a single-player Sudoku game developed by Tamas Bereczki (“we”, “us”, “our”). The app is designed so that we do not directly collect personal data from users, we do not operate developer-run servers, and we do not use analytics or advertising SDKs. This page explains the limited data the app interacts with through Apple’s platform services and your device.

1. Data stored on your device

The following information is stored locally in UserDefaults on the device where you installed the app:

• Your casual saved game and one in-progress save per Daily Challenge date (puzzle, entries, notes, selection, visible region, elapsed time, Zen flag).
• App settings (sound effects on/off, music on/off and volume, keep-screen-awake, in-app language override, appearance — System / Light / Dark).
• Local statistics (total solves, best times per difficulty, mistake-free count, notes-free count, region-switch totals).
• All-time points (a single integer).
• Run-telemetry flags (whether you ever had a conflict, ever used Notes mode, region-switch count) — used solely so achievement evaluation cannot be bypassed by resetting partway through a run.

This data remains stored locally on your device unless you choose to use the Apple integrations described below.

2. iCloud sync (Apple — your iCloud account)

If you are signed in to iCloud, the app uses Apple’s NSUbiquitousKeyValueStore to synchronize the following information between your own devices:

• Daily Challenge completion records — date key, difficulty, completion time, Zen flag, and completion timestamp. In-progress Daily saves are not synchronized and remain per-device.
• App settings — the seven preferences listed in Section 1.

This data is stored in your private iCloud key-value container associated with your Apple account. We cannot access or retrieve this information. Apple may process this data according to its own privacy policies and your account settings.

Apple’s privacy policy: apple.com/legal/privacy

3. Game Center (Apple — your Apple ID)

If you choose to sign in to Game Center, the app submits the following information to Apple’s Game Center service:

• Best completion times to up to five leaderboards — Ichi, Ni, San, the rolling Daily Challenge leaderboard, and the all-time Points leaderboard.
• Achievement progress for the eleven in-app achievements (incremental percentage for counter-based achievements, or 100% upon unlock).
• A 31-bit non-reversible hash of the puzzle string in the score’s context field, used solely for internal audit and duplicate prevention purposes. The hash is never displayed in the UI.

The app deliberately does not submit:

• Zen Mode runs (no scores, achievements, or statistics are recorded).
• Incomplete runs.
• Runs outside a plausibility window — under 30 seconds for Ichi, 60 seconds for Ni, 90 seconds for San, or longer than seven days.
• The same run more than once (deduplicated by a per-run UUID).

Your Game Center display name may appear on leaderboards according to your Apple account and Game Center privacy settings — see Settings → Game Center on your device to manage visibility.

The app does not receive your Apple ID, email address, or other personally identifying Game Center account information. Apple may process Game Center data according to its own privacy policy.

4. In-App Purchases (Apple — App Store)

The Supporter Edition is a one-time non-consumable purchase processed by Apple through StoreKit.

The app reads your entitlement status using Transaction.currentEntitlements. We do not receive your payment method, billing address, or Apple ID.

See the Terms of Use for information about what the Supporter Edition unlocks.

5. App Store review prompt

After a non-Zen completion, the app may request that Apple’s StoreKit display the native “Rate this app” prompt.

Apple — not us — controls when and how often this prompt appears (typically limited by Apple to a small number of displays per year and app version). Reviews submitted through this prompt are published on the App Store under the display name associated with your App Store account.

We can only see reviews that are publicly visible on the App Store.

6. What we do not do

• No analytics SDKs, attribution SDKs, advertising SDKs, or crash-reporting SDKs.
• No use of the IDFA (Advertising Identifier).
• No developer-operated servers, analytics services, advertising services, or third-party tracking requests. Apple frameworks such as Game Center, iCloud, and StoreKit may communicate with Apple’s services.
• No tracking across other apps or websites.
• No sale or sharing of personal data by us.

7. Children

The app is intended for a general audience and does not knowingly collect personal data from children or adults.

If you have concerns about a child’s Game Center participation, Apple’s Family Sharing and parental control features govern those settings.

8. Your rights

Because we do not store or process personal data on our own servers, we generally do not have personal data to access, export, correct, or delete on behalf of users.

To remove locally stored app data, you may delete the app from your device. Removing the app will remove its local sandboxed storage from the device.

To remove iCloud-synchronized data, you may sign out of iCloud or disable Muzukashii under Settings → Apple ID → iCloud → Apps Using iCloud.

Game Center data and leaderboard participation may be managed through your Apple ID and Game Center settings.

If you are located in the EEA or UK, applicable privacy laws such as the GDPR and UK GDPR may provide rights including access, rectification, erasure, restriction, portability, and objection. Because we do not store or process personal data on our own servers, these rights are generally exercised through your device settings or Apple’s services. Any data processed by Apple is governed by Apple’s own privacy policy.

9. Changes

We may update this Privacy Policy as the app evolves. Material changes will be reflected by updating the effective date at the top of this page.

10. Governing law

This Privacy Policy is governed by the laws of Romania, without regard to conflict of law principles.

11. Contact

Questions, requests, or anything else: [email protected].