Applies to the mobile game Mahjong Mosaic
(io.nestengineering.mahjongmosaic) on Android and iOS.
Last updated 15 October 2026.
Mahjong Mosaic has no accounts and no sign-up. We never ask for your name, your email address or your phone number, the game never asks your device where you are, and we do not use your internet address to work out where you are. What the game sends is listed below in full.
Mahjong Mosaic is made by Nest Engineering, the data controller for the purposes of the GDPR. For any privacy question, or to exercise any of the rights described below, write to support@nestengineering.io.
On first launch the game asks which age range you are in: under 13, 13–15, 16–17, or 18 and over. Only the range is kept, on your device; we never ask for or store a date or year of birth. The game is the same for everyone — the answer decides which ads are suitable and what may be collected, as set out below and under Children. Until it is answered, nothing in the table below is sent.
The save file itself never leaves your device. Your progress — levels and stars, pictures and albums, coins, gems, Lucky Spins, boosters, quests, settings and language — is written to the app’s own storage. There is no cloud save and no login, we hold no copy, and we cannot restore it for you. Deleting the app deletes it permanently.
Settings shows sign-in options for Game Center, Google Play Games and Facebook, and a cloud save option. In this version they are not connected to any service: nothing signs you in, nothing is linked to an account, and nothing is uploaded when you use them.
Some of the same numbers do travel in the analytics events described below — how far you have played, your coin and gem balances, whether you have VIP or have removed ads. They travel as individual events tied to a random installation identifier, not as a copy of your save, and they cannot be turned back into one.
The friends, the club and its chat, the weekly league and the LIVE games you can watch are simulated on your device with computer-controlled players. They are not real people, and nothing you do in these features — your games, your messages, your gifts, your requests or your settings for being watched or shown in leaderboards — is sent to other players or to us. No one else can watch you play. Your invite code is made on your device; it only leaves it if you copy it and share it yourself.
| Data | Why | Who receives it |
|---|---|---|
| Gameplay events App launches and session length, screens opened, levels started, won, lost or left, tutorial steps, coin and gem balances and what changed them, boosters, offers and ads shown and their outcome, your answer’s consent status, and frame-rate and stutter measurements. Each event also carries the app version, platform, OS version, device model, graphics chip, memory size, quality setting, the game’s language, how far you have played, how many days since install, and whether you have VIP or have removed ads. |
To understand which levels are too hard, where players stop playing, whether the game runs smoothly on a given phone, and whether a change made the game better or worse. | Mixpanel |
| An installation identifier A random string the app generates the first time collection is allowed, stored on your device. |
To tell one player’s events apart from another’s without knowing who either of them is. | Mixpanel |
| Advertising data Handled by Google’s ad SDK. May include your device’s advertising identifier (on iOS only if you allow tracking, see below), IP address, device and OS information, and which ads you were shown — subject to your age range and consent choices, see below. The game tells Google whether your age range calls for child-directed or under-age treatment; it never sends the range itself. |
To show ads, to cap how often you see them, and to measure them. | Google AdMob |
| Install attribution (Android and iOS, ages 16 and over) When you first open the game an installation record is sent so we can tell which advertisement brought you here. It includes your device’s advertising ID (on iOS only if you allow tracking when asked; otherwise Apple’s privacy-preserving attribution is used instead), device and OS information and your IP address. Afterwards a short list of milestones is sent: each new furthest level you reach with the stars earned there, finishing the tutorial, and reaching levels 10, 25, 50 and 100. AppsFlyer’s answer — whether the install came from an advertisement, and which advertising source and campaign — is also recorded in our analytics (Mixpanel). When this happens: only if your age range is 16 or over and only when analytics is allowed — in places where the game shows a consent form (such as the EEA and the UK), only once you have given consent in it. If you later withdraw that consent in the game’s privacy options, attribution stops. |
To know which advertisement or campaign an install came from, and to measure whether our advertising is worth buying. | AppsFlyer |
| Purchases Which product you bought or tried to buy, and whether it completed, failed or was restored. Attempts that fail or that you cancel are recorded too. Never your card number, billing address or store account. |
To deliver what you bought, to keep a subscription active, to restore purchases, and to find out where purchases break. | Apple / Google, RevenueCat, and Mixpanel. RevenueCat keeps your purchases under a random identifier it creates for your installation — not your name, email or store account. This one runs for every player regardless of age range, because without it a purchase cannot be delivered or restored. Where install attribution (the row above) is running, AppsFlyer’s identifier for your installation is also given to RevenueCat, and RevenueCat reports your purchases (product, price, currency) to AppsFlyer so a purchase can be linked to the advertisement that brought you; withdrawing consent removes that link. |
It is a random value created by the app itself and kept in the game’s own storage. It is not your device’s advertising ID, not a hardware serial, and not shared with any other app. If you withdraw consent it is deleted, together with any events not yet sent, and a new, unrelated one is made if collection is allowed again. Uninstalling the game destroys it.
Every request any app makes carries your IP address, and the services above receive it as part of the connection. We ask Mixpanel not to use it to locate you and not to store it on events. Google and AppsFlyer use it as described in their own policies.
On Android the game can remind you, at most once a day, that a daily reward is waiting, that Lucky Spins are ready or the piggy bank is nearly full, that the league week is ending, or that you have not played for a few days. These reminders are planned and scheduled on your device by Android’s own alarm service. There is no push server: nothing about them is sent to us or to anyone else. You can switch each kind off in the game’s Settings, or turn off the game’s notifications in your device settings.
Mahjong Mosaic shows ads between some levels, and optional ads you choose to watch in exchange for a reward. Ads are served by Google AdMob.
Google’s handling of this data is governed by the Google Privacy Policy and how Google uses data from apps that use its services.
All payments are taken by Apple or Google. We never see or receive your card number, your billing address or your store account details. The VIP subscription renews through your store account until you cancel it there; see the Terms of Service. Lucky Spins are never sold, and the Lucky Slots involve no money.
Analytics events are kept only as long as they are useful for improving the game, under the retention limits of Mixpanel. Advertising data is kept by Google, attribution data by AppsFlyer and purchase records by RevenueCat, each under its own retention policy, linked under Third-party services below. Data on your device is kept until you delete the app.
If you are in the EEA, the UK, Switzerland, California or another region with comparable law, you have the right to access, correct, delete, restrict, port or object to the processing of your personal data, and to withdraw consent at any time.
To delete what is stored on your device and start over with a new, unrelated installation identifier, use Settings › Data › Delete my data in the game. It deletes your progress on this device and drops any events not yet sent; it cannot reach data already held by the services above.
To exercise any of these, email support@nestengineering.io and tell us your device model and roughly when you installed the game. We respond within 30 days. You also have the right to complain to your local data protection authority.
We hold no account for you and the installation identifier exists only inside the app on your device, so we have no reliable way to match a request by email to a particular set of analytics events. That is a consequence of collecting as little as we do — and it is why the most complete step available to you is to uninstall the game, which destroys the saved game, the installation identifier and the link between you and what was already collected. Attribution and purchase records held by AppsFlyer and RevenueCat are not on your device, so uninstalling cannot erase them; to have those deleted, email us with the approximate date you installed the game and, if you made a purchase, its date.
Mahjong Mosaic is rated for adults (18+ on Google Play, PEGI 18, ESRB Mature 17+) because it contains simulated casino games played with in-game spins, and it is intended for players aged 18 and over. It is not directed at children and is not enrolled in Google Play’s Designed for Families programme. The age question still protects anyone younger who installs it anyway; for players who say they are under 13:
If you are a parent and want a child’s data removed, email support@nestengineering.io; deleting the app stops any collection immediately.
On Android 13 and later the game asks once, after explaining why, for permission to show notifications, so that the reminders described above can appear; you can refuse it and the game works the same, without reminders. On iOS the only permission the game asks for is Apple’s App Tracking Transparency, for players aged 18 and over, as described under Advertising and your consent above; you can refuse it and the game works the same. The game does not use your location, camera, microphone, contacts or photos.
Our service providers process data in the United States and the European Union. Where data leaves the EEA it is transferred under the European Commission’s Standard Contractual Clauses or an adequacy decision.
If we change what the game collects, we will update this page and change the date at the top. Material changes will also be announced in the app.