Last updated 14 August 2026. Applies to all Millstone Studios apps, including Sudoku at the Museum, Painting at the Museum, and The Puzzle Museum, on every platform we release on.
We don't collect personal information. There are no accounts, no ads, and no trackers in our apps. Anything you'd call "your data" — puzzle progress, settings — stays on your device.
Our apps do not collect, store, or transmit any personally identifiable information (PII), such as your name, email address, or location.
We use Firebase to collect anonymous usage data — things like which screens are used and how often — to help us understand what's working. This data is aggregated and cannot be traced back to you individually.
We may also receive anonymous, aggregated technical data automatically via the app stores we distribute through — for example, sales figures and anonymised crash reports — which cannot be traced back to you individually. We do not run advertising or ad-tracking SDKs.
Puzzle progress, preferences, and purchase status are stored on your device and synced across your devices via your private iCloud account, so a single user's progress carries over between an iPhone, iPad, or Mac. This information is tied to your Apple ID for sync purposes only — it is never visible to us or shared with any third party.
Some apps offer optional in-app purchases — such as additional content or unlimited hints. These support Family Sharing, so a single purchase can be shared across your household under Apple's Family Sharing rules. Purchases are tied to your app store account for delivery and restore purposes only.
All purchases are processed entirely by the app store you download from — the Apple App Store today, and Google Play, the Mac App Store, or Microsoft Store as we expand to those platforms. We never see or store your payment details. See that store's own privacy policy for how it handles purchase data.
Because we don't collect personal information from anyone, our apps don't knowingly collect personal information from children either.
If a future version of an app needs to collect any personal information, we will update this policy first, explain clearly what's collected and why, and — regardless of what the law requires — we will never sell or share that information with third parties for advertising or marketing purposes.
Questions about this policy can be sent to privacy@millstonestudios.uk.