Sudoku Museum — privacy policy
Last updated 2026-08-18
A sudoku game that barely needs to know anything about you. No sign-up, no profile. What it does need is set out below, together with what Google picks up through the bits of the app that are Google's rather than mine.
Who is responsible
Marcel Meijer. Contact: info@kynto.eu.
What stays on your device
Your progress, your museum, the artifacts you've dug up, your settings and your stats all live on the phone. Uninstall the game and they go with it.
Playing together, and the daily puzzle
Two things here talk to a server: solving a grid with someone else in real time, and the daily puzzle everyone gets. Both run on Google Firebase.
- An anonymous identity. Firebase Authentication hands each installation an anonymous identifier, so the two halves of a shared puzzle can find each other and a tournament score has something to attach to. It isn't tied to an email address, a Google account or a name, and there's nothing for you to sign in to.
- What actually gets sent. While you're in a shared session, the moves made in that grid. Nothing else about your device goes anywhere.
- The daily tournament. Your time, plus a display name if you pick one. Put in whatever you like — nobody verifies it and it isn't you.
Advertising
The game shows ads through Google AdMob. That's a Google service, it uses the Android advertising ID, and it collects data under Google's policy rather than this one. Where the law says so, you're asked for consent before a personalised ad loads, and your answer is what applies.
You can reset or delete the advertising ID whenever you want, in Android's settings under Privacy. That limits what AdMob can join up over time.
Purchases
Anything you buy goes through Google Play Billing. Google takes the payment and the game never sees your card details, only whether you bought the thing.
Notifications
If you let it, the game can send you a notification about the daily puzzle or about someone joining your shared session. That runs on Firebase Cloud Messaging, which needs a token identifying the installation. Turn notifications off in Android's settings and the game carries on working.
Children
The game suits a general audience. It isn't aimed at children under 13, and you don't need an account, a name or any contact details to play it.
Your rights
There's no account, so there isn't much to ask for. Uninstalling clears out everything held on the device. If you want to ask about the anonymous identifier or a tournament entry, write to info@kynto.eu, though you'll have to tell me the display name you used — nothing on my end connects that identifier back to you. You can also complain to your national data protection authority, which in the Netherlands is the Autoriteit Persoonsgegevens.
Changes
If this policy changes, the date at the top changes with it.