What data the app and the website process, why, who receives it, how long it is kept and how to exercise your rights.
Gemelos a la Vista · StackooLast updated: 2 October 2026. This policy replaces earlier versions. The Spanish version is the reference text if the two differ.
In short
You can play without an account and without the league: your progress stays on your iPhone.
The account is optional and only saves your progress in the cloud.
If you join the league, your group sees your nickname, avatar, league and points; never your email or your name.
Ads are served by Google AdMob and, depending on your region, we ask for your consent first; if you do not give it, you only see limited ads.
We use no analytics or crash reporting of our own, and the website uses no cookies.
You can delete your account and data from the app, or by writing to us.
1. Data controller
The controller is Daniel Quesada Millan, a sole trader (autónomo) with tax ID (NIF) 74385050Z and address at Calle Rambla 6 3 20, 03330 Crevillent (Alicante), España, who publishes the app under the Stackoo brand.
Each processing activity is summarised here. Those that depend on an account or on the league only exist if you take that step.
Progress and settings on your iPhone
Data
Levels and stars, challenges, streak, settings and the “No Ads” purchase entitlement.
Why
So the game works and remembers where you left off.
Recipients
Nobody. It is stored only on your device and uninstalling the app removes it.
Optional account
Data
A user ID and the sign-in method (Apple, Google or email). With email or with Apple/Google, also your email and, if the provider supplies it, your name. With Apple's “Hide My Email” we only get a relay address. And technical connection data (IP address, app and system version) that Google uses to provide and protect the service.
Why
To sign in and save your progress in the cloud.
Legal basis
Performance of the service you request when you create the account (GDPR art. 6.1.b).
Recipients
Google (Firebase Authentication), as processor.
Progress in the cloud (account only)
Data
Stars per level, daily challenges, medals, streak and counters. No name, no email, no settings and no purchase data.
Why
So your progress follows you if you change iPhone.
Legal basis
GDPR art. 6.1.b.
Recipients
Google (Firestore), as processor. Only you can read it.
Weekly league (only if you join)
Data
An anonymous identity (or your account's), your nickname, avatar and frame, your league, your points, the group and the week, and your weekly results. And technical connection data (IP address, app and system version) that Google uses to provide and protect the service.
Why
To form groups, rank players, promote and relegate, and award chests.
Legal basis
GDPR art. 6.1.b: it is the service you ask for when you join.
Who sees it
The players in your group see your nickname, avatar, frame, league and points. Only you see your results. More in section 6.
Nickname reports
Data
Who reports, who is reported and their nickname, the group, the week and the date.
Why
To keep the league respectful and answer reports.
Legal basis
Legitimate interest in protecting players (GDPR art. 6.1.f) and a legal obligation to provide a notice mechanism for illegal content (GDPR art. 6.1.c in conjunction with art. 16 of Regulation (EU) 2022/2065, the DSA).
Who sees it
Only us. The app cannot read reports.
Ads (Google AdMob)
Data
Advertising identifier (IDFA) if you allow tracking, device identifier, IP address and approximate location, ad interactions and diagnostics.
Why
To show ads and measure how they perform.
Legal basis
Your consent (GDPR art. 6.1.a) for personalised ads. Limited ads are served by Google as its own controller.
Recipients
Google, which acts as controller of that data under its policy. Details in section 3.
“No Ads” purchase
Data
Apple handles the purchase. We do not receive your payment details or store them on our servers.
Why
To charge for the purchase and check that you own it.
Recipients
Apple, under its own policy.
Support by email
Data
Your email address and whatever you tell us.
Why
To answer your question or request.
Legal basis
Handling what you ask of us (art. 6.1.b) and, where applicable, a legal obligation (art. 6.1.c).
Recipients
Cloudflare, which forwards the email to our inbox (Email Routing), and Google (Gmail), where we receive and answer the email.
We do not sell your data. We do not profile you or take automated decisions with legal effects. We do not ask for your age or real name to play.
3. Ads and consent
The app shows ads with Google AdMob. This is what it actually does:
Your first session has no ads: the ads SDK is not loaded and no permission is requested.
From the second session, before the first ad a one-sentence screen explains it. Then, in the European Economic Area and the United Kingdom, Google's consent form (UMP) appears. To be able to show it to you, the app starts Google's SDK first; no ad is requested until you decide. If you do not give consent, Google can only show you limited ads, which do not use your data to personalise them; if there are none, you see no ads.
On iOS you are also asked for the tracking (ATT) permission right before the first ad. If you decline, ads continue without the advertising identifier, and you can play all the same.
Interstitial ads appear only between levels and with no sound. The rewarded video only plays if you ask for it to get an extra hint.
On tracking, you can change your choice at any time in iOS: Settings → Privacy & Security → Tracking.
The one-time “No Ads” purchase is processed through Apple's App Store. The app only asks Apple (StoreKit) whether you own it. The entitlement is stored on your iPhone and does not depend on having an account with us. Refunds and payment claims are handled by Apple.
5. Optional account
Playing without an account is the default and the game never asks for one. If you decide to save your progress, you can sign in with Apple, Google or your email and a password. Authentication is provided by Firebase Authentication (Google). With email, Firebase sends you the verification message and, if you ask, the password reset message. We never see your password.
Without a session, the app does not communicate with Firebase. You can sign out (your progress stays on the iPhone) or delete the account.
6. Weekly league
The league is optional: it does not start until you tap join. Until you do, your nickname and avatar exist only on your iPhone.
What is created when you join
An anonymous Firebase identity (if you already have an account, it uses yours and the league stays the same).
A profile with your nickname, avatar, frame and league. The nickname starts out random, has 3 to 20 letters or digits, is unique and you can change it once every 7 days.
Each week, a row in a group of up to 30 real players with your points. It is created when you earn your first points of the week.
A weekly result (rank, promotion or relegation, chest) that only you see.
Who sees what
The other players in your group see your nickname, avatar, frame, league and points. Technically, the row the app reads also includes an internal user identifier (it is not your email), when you joined, the time of your latest points (used to break ties) and your points for the day. It does not include your email, your real name or your location. The database rules prevent anyone from reading the rows of a group they are not in.
Reporting and hiding
Any row can be reported or hidden with a long press. A person reviews reports; if a nickname breaks the rules, we replace it with a random one. Hiding a player only affects your iPhone. One report per person and week is accepted against each player.
Leaving the league
If you play without an account, you can leave and delete your league data at any time from your league profile or from Settings. If you have an account, deleting the account (Ajustes → Cuenta → Borrar cuenta (Settings → Account → Delete account)) also deletes your league data. See what is deleted and when.
7. How long we keep it
Data
Retention
Data on your iPhone
Until you uninstall the app or erase it.
Account and progress in the cloud
Until you delete the account.
League profile and weekly results
For as long as you do not leave the league or delete the account.
Weekly group rows (nickname, avatar, points)
8 weeks after the week closes. Removed automatically.
Marker of your last nickname change
8 days.
Reports
90 days.
Support emails
As long as needed to answer you and, after that, only what the law requires.
Ad data (Google)
Under Google's policy.
Website server logs (Cloudflare)
Under Cloudflare's policy.
When something is deleted, Google may keep residual copies for a limited time under its own data processing terms.
8. Recipients and international transfers
Google (Firebase Authentication and Firestore) as processor of our account and league data. The Firestore database is hosted in a European Union region. Authentication is a global Google service.
Google AdMob, as controller of the ad data.
Apple, which runs the App Store and processes purchases.
Cloudflare, which hosts this website and forwards the support email.
Google (Gmail), where we receive and answer the support email.
Google, Apple and Cloudflare may process data outside the European Economic Area, in particular in the United States. These transfers rely on the European Commission's standard contractual clauses or on the EU-US Data Privacy Framework where the provider is certified.
9. Your rights
You can exercise your rights of access, rectification, erasure, restriction of processing, portability and objection, and withdraw your consent at any time without affecting what was already processed.
Erasure: from the app, in Ajustes → Cuenta → Borrar cuenta (Settings → Account → Delete account) and in the league. More at Delete account.
Other rights: write to [email protected]. We may ask you to confirm your identity from the email of your account or by giving your nickname and avatar.
We reply within one month. If you think we have not handled your data properly, you can complain to the Spanish Data Protection Agency (aepd.es).
10. Children
The app is not aimed at children. In Spain, a minor can only consent to the processing of their data from the age of 14 (article 7 of Organic Law 3/2018). Below that age, authorisation from a parent or guardian is needed. We do not ask for the player's age. If you believe a child under 14 has given us data without that authorisation, write to [email protected] and we will delete it.
11. This website
The website uses no cookies, no analytics and no third-party resources: fonts and images are served from the site itself. Cloudflare, which hosts the website, logs technical data about each visit (such as the IP address) on its servers to provide and protect the service.
12. Security
All communications from the app and the website are encrypted. The database rules limit what each player can read and write: only their own progress and profile and, from others, only the row the league shows to their group (with the internal identifier described in section 6) and, to find out whether a nickname is free, the reservation of that nickname, which includes the internal identifier of whoever holds it. Nobody can list the nicknames or read the rows of another group.
13. Changes to this policy
If we change something important, we will update this page and the date above, and tell you in the app when the change significantly affects you. The version in force is always the one you see here. There is also a Spanish version; if they differ, the Spanish one prevails.
