Privacy policy

Last updated: 4 November 2026

This policy explains what data the Android app Luxel: Daily Light Puzzle (package app.luxel, “Luxel”, “the app”) processes and why. In short: Luxel has no account and no server of its own. Your progress stays on your device. Some data is processed by Google services the app uses for ads, purchases, analytics and crash reports.

Who is responsible

Ondřej Růžička, Czech Republic (the developer and data controller). Contact: ruzicka.ond+luxel@gmail.com.

Data stored on your device

Your puzzle progress, statistics, streak, settings (for example the daily reminder) and the record of what you have purchased are stored only in the app's storage on your device. The developer does not receive this data. If Android backup is turned on, Android may back this data up to your Google account and restore it on a new device; this is handled by Google under your Google account settings. Uninstalling the app deletes the data from the device.

The daily reminder is a local notification scheduled on your device; no push server is involved.

Purchases

Purchases (the Full game) are processed by Google Play. The developer does not receive your payment details. The app only receives from Google Play which products you own, so it can unlock them.

Ads (Google AdMob)

The app shows only rewarded ads, and only when you choose to watch one (for example to get an extra hint). Ads are provided by Google AdMob. To show ads, measure them and prevent fraud, Google may process your device's advertising ID, IP address (and an approximate location derived from it), device and app information and ad interactions.

In the European Economic Area, the United Kingdom and Switzerland the app asks for your consent with Google's consent form before ads or analytics use your data. If you do not consent, you can still watch ads, but they will not be personalised. You can change your choice at any time in Settings → Privacy. You can also reset or delete your advertising ID in your Android settings.

Analytics and crash reports (Google Firebase)

To understand how the game is played and to fix bugs, the app uses Firebase Analytics and Firebase Crashlytics:

• Analytics: anonymous gameplay events such as a puzzle started or solved, a hint used, a result shared, a widget added, the paywall shown, a purchase or the reminder turned on, together with an app instance identifier, device model, Android version, app version, language and country. No names, e-mail addresses or puzzle solutions are sent. Analytics data is not used for advertising.
• Crash reports: when the app crashes, a technical report (stack trace, device model, Android version, app version, free memory and similar device state) and an installation identifier.

In the European Economic Area, the United Kingdom and Switzerland, analytics and crash reports are only collected after you consent (and stop when you withdraw consent in Settings → Privacy). Elsewhere they are collected by default; contact us if you want your data deleted. Analytics data is kept for at most 14 months, crash reports for 90 days.

Legal basis (GDPR)

• Consent (Art. 6(1)(a) GDPR) for personalised ads, analytics and crash reports.
• Performance of a contract (Art. 6(1)(b)) for purchases.
• Legitimate interests (Art. 6(1)(f)) for showing non-personalised ads you chose to watch and for preventing ad fraud.

Who receives the data

Only Google (Google Play, AdMob, Firebase) as described above. Google may process data outside the EU; such transfers are covered by the EU–US Data Privacy Framework and Google's standard contractual clauses. See how Google uses data from apps that use its services and the Google Privacy Policy. The developer does not sell your data.

Security

All data sent by the app is encrypted in transit (HTTPS).

Children

Luxel is intended for people aged 13 and older and is not directed at children.

Your rights

You have the right to access, correct and delete your data, to restrict or object to processing, to data portability and to withdraw consent at any time (in Settings → Privacy). Because the developer does not know who you are, please include your app instance identifier or describe your device when you write. You can also lodge a complaint with a data protection authority; in the Czech Republic it is the Office for Personal Data Protection (uoou.gov.cz).

Changes

If this policy changes, the new version will be published on this page with a new date.