Privacy Policy

Last updated: June 29, 2026

This Privacy Policy explains how Crux Chess Puzzles ("the app", "we", "us") handles your information. By using the app you agree to this policy. If you do not agree, please don't use the app.

1. Information we collect

• Account identifiers. The app signs you in with an anonymous Google Firebase account and stores an anonymous account identifier and a randomly generated friend code. No name, email, or phone number is required to play.
• Profile & gameplay statistics. To power your stats, the leaderboards, and personalized recommendations, we store gameplay data in the cloud (Google Firestore), including your display name, chess rating (Elo) and rating history, number of puzzles solved, streaks, and per-puzzle attempt records (such as the puzzle, outcome, solve time, and accuracy). A copy of your progress is also kept on your device.
• Optional Google account linking. If you choose to link a Google account (to keep your progress across devices or reinstalls), we receive your Google display name and the email address associated with that account through Firebase Authentication. This is entirely optional and only happens when you explicitly link an account.
• Social features. If you add friends, appear on leaderboards, or send/accept challenges, your display name and public stats (such as rating and puzzles solved) are visible to other players. You control this with the leaderboard visibility setting (Public, Friends, or Private). If you report another player, we store the report so we can review it.
• Notifications. If you allow notifications, we store a device messaging token (Firebase Cloud Messaging) so we can send you challenge alerts. You can turn notifications off at any time in your device settings.
• AI coaching summaries. If you use the optional AI daily summary, a small set of non-identifying performance figures (for example your rating, accuracy, current streak, and the names of your strongest/weakest puzzle themes) is sent to Google's Gemini API through our secure server to generate a short, personalized coaching message. Your account identifier, name, and email are not sent to the AI. The generated text is cached briefly to limit repeat requests.
• On-device data. Your puzzle progress, review scheduling, unlocked cosmetics, app preferences, and detailed performance metrics are stored locally on your device and are not, by themselves, transmitted.
• Advertising data. The free version of the app shows ads through Google AdMob. AdMob and Google may collect and process your device's advertising identifier, device information, and approximate (IP-based) location to serve, limit, measure, and—where you have consented—personalize ads. The optional "Remove Ads" subscription disables these ads.
• Purchase data. The optional "Remove Ads" subscription is processed by Google Play Billing. Google handles the transaction; we do not receive or store your payment card details. We store only whether your subscription is active so we can disable ads.
• Consent signals (EEA/UK). Where required, we use Google's User Messaging Platform to ask for and record your consent choices for personalized advertising.

2. How we use information

• To run the game, save your progress, and show your statistics.
• To recommend puzzles suited to your skill level.
• To power social features: friends, leaderboards, and challenges.
• To generate optional AI coaching summaries.
• To send challenge notifications (if you allow them).
• To display ads and, with your consent, personalized ads.
• To provide the optional ad-free subscription.
• To maintain security, review reports, and prevent abuse.

3. How information is shared

We do not sell your personal information. Data is processed by the service providers that power the app, acting on our behalf or under their own policies:

• Google Firebase / Firestore — accounts, stats, and social features
• Google Firebase Cloud Messaging — push notifications
• Google Gemini API — optional AI coaching summaries (non-identifying stats only)
• Google AdMob & User Messaging Platform — advertising and consent
• Google Play Billing — subscription payments

Public profile information (display name and stats) is also visible to other players through leaderboards, friends, and challenges, according to your visibility setting. Your use of these services is also governed by Google's Privacy Policy.

4. Data retention & deletion

On-device data stays until you clear it, uninstall, or use the in-app delete option. You can delete your data at any time from Settings → Delete my data, which erases your local progress and your cloud account and stats. If you have already uninstalled the app, you can request deletion as described on our Data Deletion page. We process such requests within 30 days.

5. Security

Data sent between the app and our service providers is encrypted in transit. We take reasonable measures to protect information, but no method of transmission or storage is 100% secure, and we cannot guarantee absolute security.

6. Children

The app is not directed to children under 13, and we do not knowingly collect personal information from them. If you believe a child has provided us information, contact us and we will delete it.

7. Changes to this policy

We may update this policy from time to time. Changes take effect when posted here, and we will update the "Last updated" date above.

8. Contact

Questions about this policy? Email Jack321667@gmail.com.