Privacy Policy

Muzukashii (“the app”) is a single-player Sudoku game developed by Tamas Bereczki (“we”, “us”, “our”). The app is designed to minimize data collection: we do not collect personal data that identifies you, and we do not use advertising SDKs, attribution SDKs, or third-party tracking. We do collect a small amount of anonymous, non-identifying usage data, which you can turn off at any time — see Section 7. This page explains the limited data the app interacts with through Apple’s platform services, our own analytics endpoint, 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, daily reminder on/off, in-app language override, appearance — System / Light / Dark, and your anonymous-usage-sharing choice).
• 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 eight 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. Local notifications

If you enable Daily Reminder in the app’s settings, the app asks the operating system for notification permission and schedules an afternoon reminder to play the Daily Challenge.

These are local notifications: they are scheduled and delivered entirely by your device. Nothing is sent to us or to any server, there is no push token, and we cannot see whether a notification was delivered or opened. You can turn the reminder off in the app at any time, or revoke notification permission in Settings → Notifications on your device.

7. Anonymous usage analytics

To understand how the app is used and to improve it, the app sends a small number of anonymous, non-identifying events to an analytics endpoint we operate (a Cloudflare Worker at app-analytics.appsbytommy.com).

This data cannot be linked to you or your device. The app does not send — and does not generate — any identifier: no advertising identifier (IDFA), no vendor/device identifier (IDFV), and no per-install or per-user identifier. Each event is an isolated count that cannot be tied to any other event or to a person.

Each event contains only:

• The event name — one of: app installed, session started, a puzzle started, or a puzzle ended.
• Non-identifying context: the app name, app version, platform (iOS / iPadOS / macOS), and whether the build is a development or App Store build.
• For puzzle events: the game mode (normal / daily), difficulty, and — when a puzzle ends — the elapsed play time in seconds and whether it was completed or abandoned.

No personal data, purchase information, account information, free text, precise location, or device fingerprint is ever included, and the events are transmitted over an encrypted (HTTPS) connection.

IP addresses. As with any request over the internet, your device’s IP address is necessarily visible to the infrastructure that receives it. Our collector does not read, log, store, or attach your IP address to any event — the events written to storage contain only the fields listed above. Cloudflare, which operates the network the endpoint runs on, processes IP addresses transiently as a technical necessity of delivering and protecting the request, under its own privacy policy. We cannot use an IP address to identify you or to link one event to another.

Turning it off. This is enabled by default. You can turn it off at any time under Settings → Privacy → “Share Anonymous Usage”. When off, no analytics events are sent. Your choice syncs across your own devices via iCloud.

8. What we do not do

• No third-party analytics SDKs, attribution SDKs, advertising SDKs, or crash-reporting SDKs.
• No use of the IDFA (Advertising Identifier), and no device or per-user identifiers of any kind.
• No advertising services or third-party tracking requests. Aside from the anonymous, non-identifying analytics described in Section 7, we do not operate services that receive your data. 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.

9. 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.

10. 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.

11. 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.

12. Governing law

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

13. Contact

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