MahjongWalk for Android — Privacy Policy

Effective September 12, 2026

Kyohei Hakka operates the Android app MahjongWalk (the “App”). This policy explains how the Android app uses data. The iOS policy is separate.

Data used by the App

• Steps: With your permission, the App reads only step count from Health Connect to calculate in-app draws. Steps stay on your device, are not sent to our servers, and are never written to Health Connect.
• Local game data: Hands, discards, scores, and purchase entitlements are stored on your device. Ordinary solo-play data is not uploaded.
• Shared daily challenge: If you participate, Firebase anonymously assigns an app user ID. Your challenge result, discards, score, winning details, and any comment or display name you submit are sent to Firebase Firestore. Challenge statistics and comments may be visible to other users. Unfinished challenge data remains on your device.
• Analytics and device data: Firebase Analytics records app usage events and technical identifiers. Firebase Cloud Messaging processes a device token to deliver notifications; Remote Config downloads app settings. These services may process device and diagnostic information.
• Advertising: Non-Premium users may see ads served by Google AdMob. Google may process advertising and device identifiers, IP-derived approximate location, ad interactions, and diagnostics for ad delivery and measurement. See Google's advertising policies.
• Purchases: Google Play Billing processes payments. The App receives product and purchase status/tokens to enable purchased features; we do not receive payment-card details.

Purposes and sharing

We use this data to provide the game and shared challenge, maintain purchases, deliver notifications and ads, measure usage, and improve reliability. Firebase, Google AdMob, and Google Play process data as service providers under their own policies. Shared challenge submissions and comments are shown to other users as described above. Health Connect steps are not shared.

Your choices and deletion

Health Connect access and notification permission can be revoked in Android settings. The App can be used without granting step access, but step-based draws will be unavailable. Uninstalling removes local app data. Shared challenge submissions and comments may remain in Firestore after uninstalling. To request removal of your identifiable submissions, contact appkyoheihakka@gmail.com with enough details to locate them. Anonymous accounts are created automatically for the shared challenge; no email login is required.

Children and updates

The App is not directed to children under 13. We do not knowingly request their personal information. We may update this policy and will show the effective date here.

Contact: appkyoheihakka@gmail.com