Privacy Policy

Sudoku Duel · By Perrerscode · Last updated: 23 May 2026

This Privacy Policy describes how Sudoku Duel ("the App", "we", "us") handles information when you use our mobile application on iOS and Android. We have built the App to collect as little personal data as possible.

1. Information we collect

1.1 Information you provide

Nickname — an optional display name (max 20 characters) used in Versus mode, the friends list, and on the daily leaderboard. It is stored on your device and shared with opponents in rooms you join, with people you add as friends, and — if you participate in the daily leaderboard — with other players viewing today's board. It is not linked to your real identity.
Friend code — a 6-character public handle (e.g. AB12CD) issued by our backend the first time you open the app. You can share it with people you know so they can add you as a friend; they share theirs with you. The friend code is the only way to discover another player in the App — we never look up users by phone number, email, or any other identifier.
Friends list & invites — when you add a friend by their code, we store the pair (your device, their friend code + nickname) on our backend so the list survives reinstalls and so we can route challenge invites between you. Invites carry only the room code and chosen difficulty; they expire after 5 minutes and are deleted from our servers as soon as they are accepted, declined, or expire.

1.2 Information collected automatically

Data	Purpose	Where it goes	Retention
Device type, OS version, app version	Crash diagnostics, analytics	Sentry, PostHog	90 days
Crash logs & stack traces	Fix bugs	Sentry	90 days
Anonymous usage events (screen views, game completions, VS races)	Improve the App	PostHog	12 months
Approximate region (from IP, never stored verbatim)	Aggregate metrics	PostHog	12 months
Advertising identifier (IDFA on iOS / AAID on Android)	Ad delivery & frequency capping	Google AdMob	Per Google policy
VS room code, ephemeral player ID, game progress	Run live races	Cloudflare Workers (our backend) — discarded when room closes	Up to 1 hour
Random device identifier (UUID) + nickname + daily score	Display the daily leaderboard	Cloudflare Workers (our backend)	7 days after the UTC date the score was set
Random device identifier (UUID) + nickname + friend code + friends list	Friends list & invite routing	Cloudflare Workers (our backend)	Until you delete the app or wipe data in-app
Push-notification token (FCM on Android, APNs on iOS)	Deliver invite & "challenge accepted" notifications	Cloudflare Workers (our backend) and Firebase Cloud Messaging / Apple Push Notification service	Until you revoke notification permission, delete the app, or wipe data in-app

The daily leaderboard is opt-out. You can disable it any time in Settings → Privacy → Join daily leaderboard; future completions will not be submitted and the leaderboard UI will be hidden. The random device identifier used for attribution is not the OS advertising id and is rotated to a fresh value whenever you delete your local data.

Push notifications are opt-in. The first time the app needs to send you a notification (e.g. you're added as a friend and someone challenges you) you will be asked to grant the OS notification permission. If you deny it, friend invites are still delivered — just by an in-app refresh when you next open the App, not as a system banner. You can revoke the permission at any time in your device's OS settings; if you do, we automatically stop attempting to push to the token.

1.3 Information we do not collect

We do not require an account, email address, phone number, or sign-in.
We do not access your contacts, photos, microphone, camera, or precise location.
We do not sell personal data to third parties.

2. Advertising

The App displays ads served by Google AdMob. On iOS, you will be asked via Apple's App Tracking Transparency prompt whether to allow tracking. In the European Economic Area, the United Kingdom, and Switzerland, you will see a Google UMP consent screen the first time you launch the App. You can change your consent at any time from Settings → Privacy. If you decline, you will still see ads, but they will be non-personalised.

3. Children's privacy

The App is rated for general audiences and does not knowingly collect personal information from children under 13 (or under 16 in the EEA). If you believe a child has provided personal information, please contact us and we will delete it.

4. Account & data deletion

You can delete all locally stored data at any time:

In the App: Settings → Delete all data. This wipes your nickname, statistics, saved game, Versus state, friends list, daily-leaderboard device identifier, and any cached invites from your device. It also instructs our backend to unbind your push notification token and rotates the device identifier so past leaderboard submissions, friend-code records, and push tokens can no longer be re-linked to a future session. The action is irreversible.
VS-mode data on our servers (room state) is automatically discarded when the room closes (typically within minutes; never longer than 1 hour). Invite records on our servers are deleted on accept / decline / 5-minute expiry, whichever comes first.
To request deletion of any analytics or crash data we hold, email perrerscode+privacy@gmail.com with the device ID shown in Settings → About. We will respond within 30 days.

5. Your rights (GDPR / CCPA)

If you are in the EEA, the United Kingdom, or California, you have the right to access, correct, delete, or port your personal data, and to object to processing. Contact us at the email above to exercise any of these rights.

6. Data security

All network traffic between the App and our servers is encrypted with TLS. Crash and analytics data is transmitted over HTTPS to the providers listed above. We do not store payment information.

7. Third-party services

8. Changes to this policy

We may update this policy from time to time. The "Last updated" date at the top of the page will reflect the most recent change. Material changes will also be announced inside the App.

9. Contact

For any privacy-related question, contact:
Perrerscode — perrerscode+privacy@gmail.com