Privacy Policy

Effective October 4, 2026

Mercury Kids is a learning game for children aged 3 to 7. It is played free in the browser at mercuryproject.cz/play.html; an iPad and iPhone app is in preparation. There are no accounts, ads, analytics or tracking. Children’s profiles and progress stay on the device and are not sent anywhere.

Who we are

The data controller is Mercury Project s.r.o., Radlická 112/22, 150 00 Prague 5, Czech Republic, company ID (IČO) 25087410. Contact: info@mercuryproject.cz.

What is stored on the device

So that the game remembers progress, it keeps the following in the browser’s storage on the device:

Children’s profiles: a nickname, a chosen picture, the language and the date the profile was created. A nickname is enough; a real name isn’t needed.
Progress: completed levels, stars, counts of attempts, wins and mistakes, when each level was completed and last played, the level in progress, whether the child has seen the tutorial, and the day-by-day history of Today’s Orbit.
Missions an adult sets for the child: the world, the number of levels, an optional due date, the device’s time zone, when the mission was created, and which levels have been completed and how many times.
Technical data for saving and merging backups: a random device identifier, change timestamps and records of deleted profiles and missions (identifier and time only, no nickname).
The game language chosen on this device.
The state of the parental gate: the number of wrong answers, the number of lockouts in a row and the time until which it is temporarily locked.

This data is strictly necessary for the game you choose to open (§ 89(3) of Czech Act No. 127/2005 Coll. on electronic communications). None of it is ever sent to us or anyone else. The game does not use the microphone, camera, location or contacts, and does not save drawings from the Sandbox.

Backup

In the grown-ups area you can download a backup of profiles and progress as a JSON file and load it again later. The file stays wherever you save it and we never see it. It contains the children’s nicknames and progress, so keep it private.

What our server sees

When you open the Mercury Kids pages or the game, our web server writes a standard access log entry: IP address, date and time, page address, browser identification and referring page. Requests for the game’s files (scripts, sounds, images, font) are not written to the access log; they appear only in the error log if loading fails (for example, a missing file). The logs are used only to run and secure the website (legitimate interest, Art. 6(1)(f) GDPR) and are deleted automatically after about 15 days. The site runs on a server of a hosting provider in the European Union, which processes this data for us as a processor. We share the logs with no one else unless the law requires it. The game uses no cookies.

Third parties

The game contains no ads, analytics or third-party code and contacts no outside servers while you play; even the font is stored on our server. If a recording for a sentence is missing or can’t play in time, the game may speak the sentence with a voice built into the device, but only one the browser marks as stored on the device. Without such a voice, the sentence is not spoken. Spoken sentences contain only game text, never anything about your child.

When you write to us

If you email us, we use your address and message only to reply and to handle your request (legitimate interest; for GDPR requests, a legal obligation). We keep emails only as long as needed to handle them and any follow-up. Our mailbox is run for us by an email service provider in the European Union. We do not transfer personal data outside the European Union.

iPad and iPhone app

The app is in preparation and will follow the same principles: data will stay in the app’s storage on the device (it may be part of a device backup you make yourself), with no accounts, ads, analytics or third-party tools. Optional purchases of extra content will sit behind a parental gate and be processed entirely by Apple through the App Store; we will never see your name or payment details, and the app will only learn from Apple which items are unlocked. If anything changes before release, we will update this policy.

Children

Mercury Kids is made for children aged 3 to 7 who play under adult supervision. The game collects no personal information from children: the nickname and progress stay on the device and never reach us. When the page is opened we see only the technical server log described above; it is used only to run and secure the website, never to identify children, build profiles or advertise. Because the game is designed not to collect personal information from children, it does not need parental consent. The grown-ups area is separated by a parental gate. We process data under the GDPR and the Czech Act No. 110/2019 Coll. on personal data processing.

Your rights and deleting data

You are in full control of the game data. Delete a profile in For grown-ups → Manage profiles; the last profile can’t be deleted. To remove absolutely all game data, clear the data for mercuryproject.cz in your browser settings, or in the app, delete the app. We have no access to this data, so we cannot view or delete it for you.

For data in our server logs and emails you have the right of access, rectification, erasure and restriction. You can object at any time to processing based on legitimate interest. Just write to info@mercuryproject.cz. We make no automated decisions and do no profiling. You may also complain to the Czech Office for Personal Data Protection (uoou.gov.cz) or to the data protection authority where you live.

Changes

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

Contact

Questions about privacy? Write to info@mercuryproject.cz.