Privacy Policy — Sudoku (working title)

Draft for the owner's review, 2026-09-14. Must be published at a public URL and linked from App Store Connect and from Settings › Research data before submission. Replace the bracketed placeholders. Keep this in sync with docs/specs/telemetry.md; if the data collected changes, this changes.

Effective date: 2026-09-15

The short version

• The app works entirely on your device. No account, no ads, no in-app purchases.
• With your participation switched on (it is on by default and can be turned off at any time in Settings), the app sends anonymous records of how you solve puzzles to our servers for a research project on how people learn Sudoku techniques.
• Those records contain no name, email, contacts, location, advertising identifier, or anything else that identifies you. They are keyed by a random identifier the app creates on your device, which you can reset.
• We never sell data, never use it for advertising, and never track you across other apps or websites.

What the app stores on your device

Your puzzles in progress, your history and statistics, your settings, and the app's estimate of which solving techniques you know. This stays on your device (and in your iCloud device backup if you have backups enabled). Deleting the app deletes it.

What the app sends to us (research participation)

When participation is on, after you finish or leave a puzzle the app uploads a log of that game containing:

• the puzzle and its computed difficulty features;
• each move you made (cell, digit, whether it was a note), with the time since the game started;
• which solving technique the app believes justified each move;
• hints you asked for and what they showed, undos, "stuck?" nudges, pauses;
• how long the puzzle took, whether you finished it, mistakes made;
• your onboarding answers about which techniques you know, and the app's technique-skill estimates before and after the game;
• the app version, the puzzle-engine version, your device model family (for example "iPhone15,2") and iOS major version;
• a random participant identifier (a UUID generated on first launch).

We do not collect or store your name, email, contacts, precise device identifiers, IP address (our server does not record it), location, or the Advertising Identifier. The upload uses HTTPS.

Why

The data supports a study of how people learn and apply Sudoku solving techniques and how puzzle difficulty should be measured for individual players. Results may be published in aggregate. Individual game logs are never published in a form that could identify a person.

Your choices

• Turn participation off in Settings › Research data. Nothing further is uploaded, and any logs waiting to upload are deleted from the device.
• Reset your participant identifier in the same screen. Future uploads use a new random identifier; we cannot link them to earlier ones.
• Ask us to delete data. Because logs are keyed only by the random identifier, you must tell us the identifier (shown in Settings) so we can find them. Contact support@jiogo.com.

Retention and storage

Uploaded logs are stored with Cloudflare R2 (region: automatic) and kept for the duration of the research project, then aggregated or deleted. Access is limited to the project owner.

Children

The app is rated 4+ and is not directed to children under 13; it does not knowingly collect personal information from anyone. Because participation logs contain no personal information, no parental consent is required, but parents can turn participation off in Settings at any time.

Game Center (optional)

If you choose to sign in to Game Center for leaderboards or achievements, Apple's Game Center privacy terms apply to that data. The app receives only your Game Center display name and scores while you are signed in and does not send them to us.

Changes

We will update this page and the effective date when anything here changes. Material changes are announced inside the app.

Contact

Jiogo, support@jiogo.com.