Information We Collect
We are committed to minimising data collection. The App is designed to function entirely on-device without requiring an account, sign-in, or any transmission of personal data to our servers.
Data Stored Locally on Your Device
The following data is created and stored only on your device using Android's local Room database. It is never transmitted to us or any third party:
- Game history: completed puzzle records including difficulty, duration, error count, and hint count.
- In-progress game state: the current board, pencil notes, elapsed time, and move history for any game you have started but not yet finished.
- Daily challenge results: a record of which daily puzzles you have completed, including date, duration, and error count — used to calculate your streak and display the calendar view.
- In-progress daily state: saved mid-session state for the current day's Daily Challenge, so you can resume exactly where you left off.
- Achievements: a local list of which achievement IDs you have earned and when.
- Scanned puzzles: if you use the puzzle-scan feature, the extracted grid is saved locally so you can play or return to it later.
- Theme preference: your chosen colour theme, stored in SharedPreferences on-device.
Data We Do Not Collect
We do not collect, store, or process any of the following:
- Your name, email address, or any other personally identifiable information.
- Your device's unique identifiers (IMEI, Android ID, Advertising ID).
- Your location or IP address.
- Crash logs or analytics events sent to our servers.
- Any camera images captured by the scan feature (frames are processed in-memory and immediately discarded).
Contact Communications
If you choose to contact us via the support form on this website, your message is
delivered directly to our email address via your own mail client (using a mailto:
link). We receive only what you type into the form; no data is routed through or stored
on our web servers.
How We Use Data
Because all data is stored locally on your device, "how we use data" is more accurately described as how the App uses data on your behalf:
Core App Functionality
- Auto-save & resume: your in-progress game state is read on app launch to restore the board exactly as you left it.
- Game history & statistics: completed puzzle records power your personal stats screen (best times, total games, win rates).
- Daily Challenge streak: completed daily records are used to compute your current and longest streak, and to fill the monthly calendar view.
- Achievement tracking: locally stored achievement records prevent already-earned achievements from being awarded again.
- Puzzle scanning: stored scanned grids let you return to a scanned puzzle across sessions.
Deterministic Daily Puzzles
The daily puzzle for any given date is generated deterministically from a date-based seed
(YYYYMMDD as an integer). No data is fetched from a server; the same puzzle
is produced on any device on the same calendar date, purely through local computation.
No Advertising or Profiling
The App contains no advertising SDK, no analytics SDK, no crash-reporting SDK, and no third-party tracking of any kind. We do not build profiles of users, and we do not use data — local or otherwise — to target advertising.
Optional Donations
If you choose to support us via a donation platform (Buy Me a Coffee, Ko-fi, PayPal, or GitHub Sponsors), any personal or payment information you provide is governed by that platform's own privacy policy. We do not receive or store payment details.
Data Security
Because your data lives entirely on your device, its security depends substantially on the security of your device itself. We recommend keeping your device up to date with the latest Android security patches and using a screen lock.
Local Database
Game data is stored in a SQLite database managed by Android's Room persistence library. On Android 10 and above, app-private storage is protected by the operating system from access by other applications. On older Android versions, the standard Android app-sandbox model applies.
No Network Transmission
The App does not make network requests. There are no API calls, no telemetry endpoints, and no background sync processes. Your data cannot be intercepted in transit because it is never in transit.
Backups
If you have enabled Android's automatic backup feature (Google One Backup / Auto Backup), your app data may be backed up to your Google account according to Android's standard backup policy. This is governed by Google's own privacy terms. To disable backup for this App specifically, you can do so in your device's backup settings.
Data Deletion
Uninstalling the App permanently deletes all locally stored game data. If you wish to clear your data without uninstalling, you can use the "Clear App Data" option in your device's Application Settings at any time.
Cookies
The Sudoku Universe Android application does not use cookies. Cookies are a web technology; the App communicates no data over the internet and therefore has no use for them.
This Website
This website (docs/website) is a static HTML/CSS/JS site served directly
from files. It does not use cookies, local storage, session storage, or any tracking
pixels. No analytics, advertising, or third-party scripts are loaded. JavaScript on this
site runs entirely in your browser and is limited to:
- Toggling the mobile navigation menu.
- Adding a scroll-triggered class to the header.
- Highlighting the active section in the sidebar table of contents.
- Powering the contact modal and composing the
mailto:link.
None of these operations transmit data to any server. The current year displayed in the footer is computed from your device clock.
Do Not Track
Because we do not track users, Do Not Track (DNT) browser signals have no functional impact on this site. There is nothing to opt out of.
Your Rights & Choices
Because Sudoku Universe stores your data only on your own device and we hold none of it on our servers, you remain in complete control of it at all times.
Access & Portability
All of your data — game history, statistics, achievements, and saved puzzles — lives on your device. You can view it within the App at any time, and Android's standard backup mechanisms let you carry it to a new device.
Erasure
You can permanently delete all of your data at any moment by choosing "Clear App Data" in your device settings, or by uninstalling the App. No copy is retained anywhere else, because no copy ever leaves your device.
Regional Privacy Rights (GDPR & CCPA)
Privacy laws such as the EU/UK GDPR and the California Consumer Privacy Act grant rights to access, correct, delete, and port your personal data, and to object to its sale. We do not collect, process, sell, or share personal data, so there is nothing on our side to disclose, correct, or delete — these rights are satisfied inherently by our on-device-only design.
Communications
If you email us or use the contact form, we retain that correspondence only as long as needed to address your request. You may ask us to delete it at any time by writing to SudokuSupport@softwaredevteam.gr.
Third-Party Links
The App and this website may contain links to external websites or services — including the Google Play Store, donation platforms, and related resources. These third-party sites operate independently and are not controlled by us.
Our Responsibility
We are not responsible for the content, privacy practices, or terms of service of any third-party site. The inclusion of a link does not imply our endorsement of that site or its content.
Google Play Store
Downloading the App through the Google Play Store is subject to Google's Privacy Policy and Terms of Service. We have no control over and assume no responsibility for data collected by Google in connection with the distribution of the App.
Donation Platforms
If you choose to donate via Buy Me a Coffee, Ko-fi, PayPal, or GitHub Sponsors, your interaction with those platforms is governed by their respective privacy policies. We encourage you to read those policies before making a donation.
Children's Privacy
The App is not directed at children under the age of 13. We do not knowingly collect any personal information from children. If you believe a child under 13 has provided personal information through our contact channels, please contact us at SudokuSupport@softwaredevteam.gr and we will take prompt steps to delete that information.
Changes to This Policy
We may update this Privacy Policy from time to time. We will notify you of any significant changes by updating the "Last updated" date at the top of this page. We encourage you to review this policy periodically. Your continued use of the App after changes are posted constitutes your acceptance of the revised policy.
Contact Us
If you have any questions or concerns about this Privacy Policy or our data practices, please contact us through the support form on our website, or reach us directly at SudokuSupport@softwaredevteam.gr.