Effective date: 13 July 2026 · Last updated: 13 July 2026
This Privacy Policy explains how Sudoku Classic (“the app”, “we”, “our”) collects, uses, and protects your information when you play. By installing or using the app, you agree to the practices described below.
If you have questions about this policy, contact us at nguyenduyanhuit1989@gmail.com.
1. Information we collect
We do not ask for your real name, phone number, photos, contacts, location, or any other identifying personal information. Sudoku Classic has no user accounts and no online profile. The data the app handles is described below.
1.1 Data you provide / that stays on your device
- Game progress — Best completion times, difficulty stats, Adventure stars, daily-challenge streak, coin balance, and power-up inventory. Stored locally on your device.
- Purchases — Whether you own “Remove Ads” (so ads stay off). Stored locally and restorable from your store account.
- Settings — Theme, language, sound/haptics, and mistake-mode preferences. Stored locally.
1.2 Data collected automatically
- Anonymous device identifier — Firebase assigns an anonymous user ID (UID) on first launch. It is not linked to your real identity and is used only to tag crash reports and analytics from the same device.
- Crash reports (Firebase Crashlytics) — On a crash we collect stack trace, device model, OS version, app version, available memory, and gameplay context (mode, level, score) to diagnose and fix bugs.
- Gameplay analytics (Firebase Analytics) — Anonymous event counts (level started / completed / failed, power-up used, ad watched, purchase made, daily login, screen views), used in aggregate to improve game balance. No personal data is attached — only gameplay/monetization metrics.
- Advertising identifier (AdMob) — Android Advertising ID or iOS IDFA, collected only if you allow ad personalization via the consent prompt (EEA/UK) or the iOS App Tracking Transparency prompt. Decline and ads still show, just not personalized.
- Purchase tokens — When you buy Remove Ads or a tip, Google Play or Apple StoreKit sends a purchase token to verify the transaction. We do not receive or store your card number, billing address, or payment details — those stay with Google/Apple.
1.3 What we never collect
- Real name, email (unless you write to support), phone number, address.
- Contacts, photos, microphone, camera, precise GPS location.
- Health data, financial accounts, biometric data.
- Web browsing history outside the app.
2. Third-party services
Sudoku Classic uses the following services. Each has its own privacy practices — please review their policies for details.
| Service | Provider | Purpose |
|---|---|---|
| Firebase Analytics | Anonymous gameplay metrics | |
| Firebase Crashlytics | Crash diagnostic reports | |
| Firebase Authentication | Anonymous user ID (crash / analytics tagging) | |
| Google AdMob | Banner / interstitial / rewarded ads | |
| Google Play Billing | In-app purchases on Android | |
| Apple StoreKit | Apple | In-app purchases on iOS |
Google privacy policy: policies.google.com/privacy · Apple privacy policy: apple.com/legal/privacy
3. How we use your data
- Make the game work — Save progress, fulfill purchases, and send any local reminders you opt into.
- Fix bugs — Crash reports help us resolve crashes.
- Improve gameplay — Aggregate analytics help us tune difficulty, reward economy, and feature priorities.
- Show ads — AdMob serves ads (personalized only with consent, otherwise contextual).
- Detect abuse — Anonymous flags prevent claiming the same rewarded-ad reward more than once.
We do not sell your data, share it with brokers, or use it for profiling outside the game.
4. Your rights and choices
4.1 Delete your data
Local data (on-device): Uninstall the app to clear all locally stored progress (best times, Adventure stars, coins, daily streak, settings). There is no in-app “Delete my data” button because there is no user account — all local data is anonymous and removed at uninstall.
Anonymous diagnostics (on Google servers): Crash reports and analytics are tied only to an anonymous Firebase UID, never to your identity. To request removal of historical crash/analytics data tied to your device, email nguyenduyanhuit1989@gmail.com with your approximate first-launch date; we action it within 30 days.
In-app purchases are tied to your Apple ID / Google account, not our servers — they remain restorable after re-install.
4.2 Opt out of personalized ads
- EEA / UK / Switzerland: Settings → “Manage ad preferences” (appears automatically per Google UMP) → toggle off personalized ads.
- iOS (any region): System Settings → Privacy & Security → Tracking → Sudoku Classic → toggle off.
- Android (any region): System Settings → Google → Ads → “Opt out of Ads Personalization”.
4.3 Opt out of analytics & crash reporting
We do not provide an in-app toggle in non-EEA regions because the data is anonymous and aggregated. EEA/UK users can decline via the first-launch consent prompt. To request removal of historical crash reports tied to your anonymous UID, email support with your approximate first-launch date.
4.4 GDPR rights (EEA / UK users)
You have the right to access the data we hold (anonymous UID + diagnostics), request erasure (see 4.1, answered within 30 days per GDPR Art. 17), object to processing for marketing/analytics (revoke consent via Settings → Manage ad preferences), and lodge a complaint with your local data protection authority.
4.5 CCPA rights (California users)
You have the right to know the categories of personal data collected (see Section 2), the right to delete (see 4.1), and the right not to be discriminated against for exercising these rights. We do not sell personal information.
4.6 Vietnamese users (Decree 13/2023/NĐ-CP)
For users in Vietnam, the same rights apply under Vietnam’s Personal Data Protection Decree (PDPD). Contact support to exercise your rights.
5. Notifications
The app may send local reminder notifications (e.g., a daily-challenge reminder) only if you grant notification permission. These are local — they fire from your device, not our servers, and no data is sent to schedule them. Disable them anytime in System Settings → Apps → Sudoku Classic → Notifications.
6. Children’s privacy
Sudoku Classic is not directed at children under 13 (or the equivalent minimum age in your jurisdiction — 16 in most EEA countries). We do not knowingly collect personal data from children. If you are a parent and believe your child has provided data, contact support and we will delete it. The app is rated Everyone / 4+ and intended for casual puzzle players of any adult age; children may play under parental supervision.
7. Security
- Network traffic between the app and Google/Apple services is HTTPS-encrypted.
- Crash reports are processed by Firebase Crashlytics under their security standards (ISO 27001 / SOC 2 / SOC 3).
- Local game progress is stored in your device’s app sandbox, inaccessible to other apps.
No system is 100% secure. We follow industry-standard practices but cannot guarantee absolute security.
8. Data retention
- Local data — stays on your device until you uninstall.
- Crash reports — retained 90 days then aggregated.
- Analytics events — retained 14 months (Firebase default).
- Purchase receipts — retained as required by Google/Apple for refund processing.
9. Changes to this policy
We may update this Privacy Policy from time to time. Material changes will be announced via an in-app message on the next launch and posted here with a new “Last updated” date. Continued use after the change becomes effective constitutes acceptance.
10. Contact
Email: nguyenduyanhuit1989@gmail.com
Subject line tip: include “Privacy” or “GDPR” so we route it correctly.
This policy was prepared for compliance with Apple App Store §5.1, Google Play Data Safety, GDPR (EU Regulation 2016/679), UK Data Protection Act 2018, CCPA, and Vietnam PDPD Decree 13/2023/NĐ-CP.