Mitsudoku — mobile application by L5L3 s.r.o.
Effective 1 September 2026 · Last updated 8 September 2026
Mitsudoku is a Sudoku game: solve a puzzle, and one fragment of a Japanese painting returns to colour. This policy explains what the game does with information while you play it. It covers the mobile app — not the rest of l5l3.cz, and not the app stores you download it from.
Mitsudoku is published by L5L3 s.r.o. (“we”, “us”). Under the EU General Data Protection Regulation we are the controller of the personal data described in this policy.
We have not appointed a Data Protection Officer; the address above reaches the people who can answer.
Everything the game needs in order to be a game is kept on your phone, in the app's own private storage. None of it is transmitted to us or to anyone else, and all of it is destroyed when you uninstall the app.
| What | Why it is kept |
|---|---|
| Puzzle progress | Which of the 850 puzzles you have solved and when, plus a snapshot of any board you left half-finished, so you can pick it up where you left off. |
| Settings | Music and sound levels, vibration on or off, reminders on or off. |
| Seals | How many red seals (lives) and blue seals (hints) you have left, and the time at which an empty row refills. |
| Guided tours | Which of the three first-run walk-throughs you have already seen. |
| Difficulty tally | How many easy, medium and hard puzzles you have started. Used only to work out the banded “favourite difficulty” described in §3.3. |
The game has no text fields, no camera or microphone access, no access to your contacts, and no access to files outside its own folder.
We use Google Analytics for Firebase to understand how the game is played across everyone who plays it — where puzzles are abandoned, whether a difficulty is misjudged, whether the seal economy stops people too often. The provider is Google Ireland Limited for players in the European Economic Area, the UK and Switzerland, and Google LLC elsewhere.
Analytics measures an installation, not a person. It is tied to a randomly generated app instance number that has no connection to your name, your email or your Google account, and that is destroyed when you uninstall the app.
Twelve, and no more. Each is a count of something that happened inside the game.
| Group | What is recorded |
|---|---|
| Puzzles | A puzzle started and a puzzle ended: which collection and painting, which cell, its difficulty, whether it was resumed, how it ended (solved, left, or out of seals), how long it took, how many mistakes, hints and restarts, and how full the board was. |
| Milestones | A painting completed, a collection unlocked, a collection completed. |
| Seals | A seal spent and why; running out of seals, and whether you chose to wait or to watch a video; a request for a rewarded video and whether it paid out. |
| Learning | A guided tour ending, and the step it reached. |
| Settings | A setting changed, and its new value — a volume percentage, or on and off. |
| Screens | Which of the game's four screens was opened. |
| Faults | A short technical code when something failed quietly: a sound that would not play, a saved board that did not match its puzzle. |
Six, all deliberately coarse so that none of them can single anyone out: how many puzzles you have solved (as a band such as “6–25”), how many collections you have unlocked, which difficulty you play most, whether music is on, whether sound is on, and whether you are on a phone or a tablet.
Your name, email address, telephone number or postal address. Your contacts, photos, files, calendar, camera or microphone. Your precise location — the game asks your operating system for no location permission at all, which is also what stops the advertising software in §4 from ever receiving one. Your browsing history, or anything you do in other apps. Health or financial information. Anything you type — the game has nowhere to type. We hold nothing that identifies you personally, and we make no attempt to work out who you are.
The game does not currently offer an in-app analytics switch. Deleting the app stops collection immediately and removes everything in §2 from your device. You can also reset or delete your Android Advertising ID in system settings, which severs the link between this installation and any other. If you would like data already collected for your installation deleted, write to privacy@l5l3.cz — but please read §9 first, because pseudonymous data is genuinely hard for us to find on request.
The advertising consent screen in §4.4 does not govern analytics. It belongs to the advertising software and controls what is described in §4; declining there stops personalised adverts and changes nothing here. Analytics rests on the basis set out in §8, which you can object to under §9.
Mitsudoku carries a single kind of advertising: an optional rewarded video. When a row of seals runs out you are offered a choice between waiting for them to refill on their own and watching a short video to get two of them back at once. Nothing is shown unless you choose it.
There are no banners, no interstitials, and no advertising of any kind while you are solving a puzzle. The game can be finished without ever watching one: the seals always return by themselves, and no puzzle, painting or collection is ever held behind an advert.
Adverts are delivered by Appodeal, Inc., 575 Market Street, 5th Floor, San Francisco, CA 94105, USA — appodeal.com/privacy-policy.
Appodeal is a mediation platform rather than a single advertiser. When you choose to watch a video, its software holds an auction on your own device between several advertising networks and shows whichever of them bids highest. The consequence matters more than the mechanism: your data does not stop at Appodeal. It is passed on to the networks taking part, and each of them decides for itself what it then does with it — in the language of the GDPR each is an independent controller, not someone acting on our instructions. Their handling is governed by their own policies rather than by this one.
Which networks are in that auction is Appodeal's arrangement and changes without a release of ours, so a list printed here would go quietly out of date — which is worse than no list. Appodeal publishes the current one, with a link to each network's policy and, where one is offered, its opt-out:
When you ask for a video, Appodeal and the networks bidding for it receive:
They do not receive your puzzle progress, your settings, or anything else listed in §2, and we attach no identifier of our own. Three things this software is capable of collecting are switched off here by construction rather than by promise: it can report a precise location only where the app holds a location permission, and Mitsudoku asks for none; and it can attach a user account or a purchase history only where the app hands one over, and the game has neither to hand.
In the European Economic Area, the UK and Switzerland a consent screen appears before the first advert is ever requested, presented by Appodeal's own consent tool. It asks whether adverts may be personalised — chosen using the identifier above and the profile built on it, rather than only from the app you are in and the country you are in.
Your answer is kept on your device in the industry-standard IAB TCF format and travels with the request to the networks in the auction, which is how they know what they may do with what §4.3 sends them. It records what you agreed to, not who you are.
You can change it at any time. Wherever that screen applies to you, the game's Settings carry an Advertising entry that opens it again. Withdrawing is exactly as easy as agreeing was, takes effect from the next advert, and does not make unlawful anything that was lawful before you withdrew.
Refusing takes neither the video nor the seals away. The reward is identical; the advert is simply chosen from the app and the country instead of from a profile. Nothing about how the game plays, or about what it gives you, depends on your answer — and we would rather say so plainly than have you agree to something in case it does.
Before any personalised advert, Apple's own dialog asks whether the game may track you across other companies' apps and websites. Declining is respected in full: the IDFA is withheld, adverts stop being personalised, and the game is unchanged. You can revisit the answer in Settings → Privacy & Security → Tracking.
On Android, you can reset or delete your Advertising ID at any time in Settings → Privacy → Ads, which severs the link between this installation and any profile built on it.
In a small number of countries under comprehensive international sanctions the advertising software is never started: no advert is requested, no consent screen appears, and nothing in §4.3 leaves the device. To decide that, the game reads the country code your mobile network already reports — from the SIM card, or from the network currently serving it. It does not look at the region you have chosen in your settings, which says what you like reading rather than where you are. That reading needs no permission, is not stored, and never leaves your device; it is used once, to decide whether to start the advertising software at all.
The game can remind you when a spent row of seals has refilled, and can nudge you after two days and after a week if a painting is left unfinished. These are scheduled by your own device, from information already on it. There is no push service and no server: nothing is sent anywhere in order to produce them, and we never learn whether one was shown.
Permission is asked for at two moments only — after you finish your first painting, and when a row of red seals runs out. You can turn reminders off in the game's Settings or in your device's notification settings, and nothing is ever scheduled between 21:00 and 10:00.
We do not sell personal data for money, and we disclose it to nobody beyond this table. §10 explains why handing an advertising identifier to an ad network nevertheless counts as “sharing” — and in several US states as a “sale” — however little money changes hands.
| Who | What they get | Their terms |
|---|---|---|
| Everything in §3, as our analytics processor. | firebase.google.com/support/privacy | |
| Appodeal | Everything in §4.3, and only when you choose to watch a video. Appodeal acts as an independent controller rather than as our processor, and passes it onward to the networks bidding in the auction, each of which is one too (§4.2). | appodeal.com/privacy-policy the networks it mediates |
| Apple, Google Play | Whatever the store itself records about a download or an update. That is their processing under their own policies, not ours, and we receive only aggregate figures. | apple.com/legal/privacy policies.google.com/privacy |
| Authorities | Only what a valid legal order compels, and only if we hold it — which, for anything that identifies you, we do not. | — |
Google processes analytics data in the United States and in other countries where it operates. For players in the EEA, the UK and Switzerland those transfers rely on the European Commission's Standard Contractual Clauses together with Google's certification under the EU–US Data Privacy Framework, and on the equivalent UK and Swiss arrangements. A copy of the safeguards is available from us on request.
Appodeal, Inc. is established in the United States, and the networks bidding in the auction described in §4.2 operate in the United States, the European Union and elsewhere. For players in the EEA, the UK and Switzerland those transfers rely on the Standard Contractual Clauses incorporated into our agreement with Appodeal, and on each network's own arrangements as stated in its policy. Because a video is shown only when you ask for one, and in those regions only after the consent in §4.4, no transfer of this kind happens without you.
Under the GDPR every purpose needs a legal basis. These are ours.
| Purpose | Basis |
|---|---|
| Running the game | Storing progress, settings and seals on your device is strictly necessary to provide the game you asked for. It is not processing by us at all — the data never leaves the device. |
| Analytics | Our legitimate interest in understanding how the game is played and improving it (Article 6(1)(f)). You can object at any time under §9, and uninstalling ends it outright. There is no in-app analytics switch, and — stated plainly because it would be easy to assume otherwise — the advertising consent screen in §4.4 does not cover analytics. That screen belongs to the advertising software and reports to us only whether consent was collected, not for which purposes, so we do not present it as a measurement control it cannot be. |
| Advertising | Your consent (Article 6(1)(a)) for personalised advertising, and for the storing of and access to identifiers on your device, collected through the screen in §4.4 and withdrawable there at any time. For non-personalised advertising, frequency capping and fraud prevention, our legitimate interest in funding a free game (Article 6(1)(f)). |
| Reminders | Your consent, given through the permission your operating system asks for and withdrawable in Settings. |
| Answering you | Our legitimate interest in replying to messages, and our legal obligation to handle privacy requests. |
If the GDPR applies to you, you have the right to ask for a copy of your personal data, to have it corrected or erased, to have its processing restricted, to object to processing based on legitimate interests, to receive it in a portable form, and to withdraw any consent you have given without that affecting what came before. Write to privacy@l5l3.cz and we will answer within one month.
One honest limitation. Analytics data is pseudonymous: it is keyed to a random installation number that we cannot connect to an email address. Article 11 GDPR covers exactly this situation — where a controller cannot identify a person, it is not obliged to acquire extra information in order to do so. In practice that means we usually cannot find “your” analytics data on the strength of a message from you. Deleting the app stops collection outright and clears everything in §2, and that remains the fastest and most complete remedy available to you.
You also have the right to complain to a supervisory authority — in the Czech Republic that is the Office for Personal Data Protection, uoou.gov.cz, Pplk. Sochora 27, 170 00 Praha 7 — or to the authority where you live or work.
If you live in California, Colorado, Connecticut, Virginia or another state with a comprehensive privacy law, this section is for you.
In the past twelve months we have collected these categories: identifiers (a random app instance number, and an advertising identifier), internet or app activity (the events in §3.2, and what became of an advert under §4.3), coarse geolocation (country and region derived from an IP address) and inferences (the banded properties in §3.3). We collect them for the purposes in §8, from your use of the app, and we disclose them only as set out in §6.
We do not sell personal information for money, and never have. But when you choose to watch a rewarded video, your advertising identifier is passed to the advertising networks in §4.2 so that they can decide what to show you — and under the CCPA as amended, and under the laws of Colorado, Connecticut, Virginia, Texas and the states that follow them, that is “sharing” for cross-context behavioural advertising, and in several of them a “sale”, whether or not money changes hands. We treat it as both, rather than relying on whichever reading suits us.
To opt out, use the Advertising entry in the game's Settings (§4.4) — it is the same control wherever you live, whether your law frames the choice as a consent or as an opt-out. You can also delete or reset your advertising identifier in your device settings, and on iOS decline Apple's prompt (§4.5). We do not collect sensitive personal information, we do not knowingly collect data from anyone under 16, and we do not profile anyone in a way that produces legal or similarly significant effects. We offer no financial incentive in exchange for data, and exercising any of these rights will never get you a worse version of the game: the video, the reward and the seals behave identically either way.
Mitsudoku is rated for players aged 13 and over and is not directed at children. It is not part of Google Play's Designed for Families programme, and the advertising in §4 is delivered on that same footing — as advertising to a general audience of 13 and over, never as child-directed advertising.
We do not knowingly collect personal information from a child under 13, or under 16 in a country where 16 is the age of digital consent. If you believe a child has provided us with something, write to privacy@l5l3.cz and we will delete it.
Everything in §2 is held in the app's private storage, protected by the operating system's own sandbox and by your device's screen lock and encryption. Everything in §3 travels to Google over an encrypted connection.
The strongest protection here is architectural rather than procedural: there is no account, no password and no server of ours holding player data, so there is no user database to breach. No system is perfectly secure and we cannot promise absolute security — but we have kept the amount of data at risk as close to nothing as a game can.
| What | How long |
|---|---|
| Everything in §2 | Until you delete it in the game or uninstall the app. We never hold a copy. |
| Analytics events | Up to 14 months from collection, after which Google deletes the event-level records automatically. Aggregate figures — totals and averages that identify no installation — may be kept longer. |
| Advertising data | Appodeal and the networks in §4.2 each set their own period and state it in their own policies. We hold none of it — we never receive it, and we keep no advertising profile of our own. |
| Messages you send us | Up to 24 months, so that we can show how a request was handled. |
When this policy changes, the date at the top changes with it. A material change is announced in the app's release notes, and where the law requires consent we will ask again rather than assume it. Earlier versions are available on request.
Anything to do with this policy — a question, a request under §9, a complaint — goes to the first address below, and a person reads it.