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Privacy policy

Last updated: October 20, 2026

The short version

This policy covers two websites run by SEQUENCODE: sequencode.dev and Solvarium (solvarium.app), where our puzzle games can be played in the browser. sequencode.dev is static, sets no cookies and has no contact form; Google Analytics runs there only if you say yes in the cookie banner. Solvarium uses Google Analytics too, likewise only if you accept in its own cookie banner. On Solvarium you can play without an account, and your progress then stays in your browser. An account is optional. When advertising is active, ads appear only inside the browser games, never on the content pages, and in the EEA, the UK and Switzerland Google asks for your consent first.

Who is responsible

Both websites are run by SEQUENCODE, Yannick Krüssel (legal notice: https://sequencode.dev/legal/imprint). Solvarium is the name of our game collection, not a separate company. So the controller under the GDPR is the same for both sites. The contact details are at the end of this page.

Server logs

Both websites are hosted on Firebase Hosting (Google Ireland Limited). Like any web server, Firebase records technical details of each request:

  • your IP address
  • the page requested and the time of the request
  • your browser and operating system (the user-agent string)
  • the referring page, if any

These logs exist so that the service can be operated and abuse can be detected. The legal basis is our legitimate interest in running a secure website (Art. 6(1)(f) GDPR). We do not use them to build profiles and do not combine them with anything else.

Google's handling of this data is described at https://firebase.google.com/support/privacy.

Each Solvarium page and game also reads one small public settings document from our database (Cloud Firestore, Google, Frankfurt region), to see which games are switched on. That request carries no account data.

The domain solvarium.app is registered with Cloudflare, which also runs its DNS. Cloudflare only answers the lookup of the name. The pages themselves come straight from Firebase and do not pass through Cloudflare.

Fonts and assets

The fonts (Montserrat Alt1 on sequencode.dev, Quicksand and Nunito on Solvarium) and the images on both sites are served from their own domain. No font is loaded from Google Fonts or any other third party.

The browser games on Solvarium are built with Flutter. When a game starts, your browser loads Flutter's drawing engine (CanvasKit) from Google's servers (gstatic.com), and fallback fonts from there too if a character needs one. As with any download, Google sees your IP address and browser for these requests. No cookie is set.

Analytics

SEQUENCODE can use Google Analytics for Firebase (GA4) to see which pages get read and how people navigate the site. This is opt-in: on your first visit a banner asks, and nothing loads and nothing is set until you accept. Declining, and simply not answering, are the same state as far as Google is concerned — no request reaches Google either way.

If you accept, GA4 may process:

  • the pages you view and how you arrived at them
  • approximate location derived from your IP address (Google does not store the raw IP for GA4 properties)
  • device, browser and operating system information

No account, name or email address is collected, and nothing collected is used to identify you personally. Your choice is remembered in your browser under sequencode-consent, and you can change it at any time from Cookie settings in the footer — accepting loads the script, declining removes it from future page loads and clears nothing already stored by Google on their side, which is why withdrawing is worth doing as soon as you decide to.

Google's handling of this data is described at https://policies.google.com/privacy and https://support.google.com/analytics/answer/12017362.

This banner and the key sequencode-consent belong to sequencode.dev only. Solvarium asks separately, in its own banner; see "Google Analytics on Solvarium" below.

Google Analytics on Solvarium

Solvarium uses Google Analytics 4 to learn which pages and games are used, where visitors give up, and how fast pages load, so that we can improve the site and the games. It runs only if you choose Accept in Solvarium's cookie banner. Until you choose, and if you choose Decline, the Analytics script is not loaded at all, no Analytics cookie is set and nothing is sent to Google.

If you accept, Google Analytics processes:

  • the pages you view, in which language, the page you came from, and on a game page which game it is
  • what you do on the site: opening a game, pressing Play, switching the language, following a link to Google Play, and signing in or creating an account (only whether with Google or with email, never your address or account)
  • in the browser games: starting, solving, restarting or leaving a puzzle (mode, difficulty, puzzle number, time taken, how full the board was), mistakes and hints taken, how far you got in the tutorial, and changed settings
  • how fast pages load and respond (Core Web Vitals)
  • device type, browser, operating system, screen size and language, and your approximate location (country, region, city) derived from your IP address. Google Analytics 4 does not log or store IP addresses
  • a random ID in the cookies _ga and _ga_ZMQCTJ32KL, so that two visits from the same browser can be told apart from two visitors. It is not linked to your Solvarium account

We have switched off Google signals and the use of this data for advertising: it is not shared with Google's advertising products, no ads are personalised from it, and no user ID or account data is sent. We only look at aggregated reports.

The provider is Google Ireland Limited, Gordon House, Barrow Street, Dublin 4, Ireland, which processes the data on our behalf under a data processing agreement. Data may also be transferred to Google LLC in the USA. Google LLC is certified under the EU-US Data Privacy Framework, so the European Commission's adequacy decision of 10 July 2023 covers that transfer (Art. 45 GDPR); Google additionally relies on the EU standard contractual clauses.

Data in Google Analytics is kept for 14 months and then deleted automatically. The cookies expire after 14 months at the latest, and sooner if you delete them or withdraw your consent.

The legal basis is your consent: for storing and reading the cookies on your device § 25(1) TDDDG (formerly TTDSG), for the processing itself Art. 6(1)(a) GDPR.

You can withdraw your consent at any time, with effect for the future: choose Cookie settings at the bottom of any Solvarium page, then Decline. Analytics stops at once, and the site deletes the _ga cookies for solvarium.app. Your choice is kept in your browser under solvarium.consent and applies to the content pages and the browser games alike, because they share one address.

Local storage

Your cookie-banner choice ("accepted" or "declined") is saved in your browser under sequencode-consent. It never leaves your device and is not a cookie: nothing is sent to the server by storing it. Clearing your browser data removes it, which means the banner asks again on your next visit.

On Solvarium, the games keep your progress and settings in your browser's local storage. If you sign in, Firebase keeps the sign-in in your browser (IndexedDB), and the site remembers your player name under solvarium.handle so pages can show it at once. Your choice in Solvarium’s cookie banner is kept under solvarium.consent. For five minutes at a time, solvarium.config in session storage remembers which games are switched on. Storing these sends nothing anywhere, and clearing your browser data removes them.

Solvarium without an account

You can play every game on Solvarium without signing in. Your progress, settings and hints then stay in the local storage of your browser, or of the app, on this device. So that your solved puzzles can count toward the daily puzzle, the week and the leaderboards, a game gives you an anonymous player ID the first time you open a board (Firebase Authentication, anonymous sign-in). It carries no name and no email address. With it we store which boards you solved and their results, so that each result is checked and counted once. If you sign in later, this anonymous player becomes part of your account and nothing is lost. If you never sign in, the ID stays tied to this browser or app; clearing its data removes it from your device, and on request we delete the stored record too. The legal basis is our legitimate interest in counting results fairly (Art. 6(1)(f) GDPR).

Solvarium accounts

An account is optional. You create one at https://solvarium.app/account with Google sign-in or with an email address and password. Sign-in runs on Firebase Authentication, a Google service. When you sign in, the progress in your browser is merged into the account and kept in sync from then on. It is then safe, and the same on every device where you sign in, including our Android apps where they offer this.

With an account we store:

  • with Google sign-in: your Google account ID and email address, and the name and profile picture link your Google account passes on (Firebase stores them; we do not show or use the name or picture)
  • with email and password: your email address, and your password only as a hash. Firebase sends the confirmation and password-reset emails
  • an internal user ID, and when the account was created and last updated
  • your progress in each game, for syncing. Purchases and hints never go into the account
  • the players you follow. Only you can see this list

Nobody else sees anything about you until you choose a player name and make your profile public. A public profile shows:

  • your player name (3 to 20 characters, unique), in the spelling you choose; only upper and lower case may differ
  • for each game: solved puzzles, campaign levels, daily puzzles, monthly trophies, and achievements with their progress
  • your place on the leaderboards of each game

You can make the profile private again at any time. It then leaves the leaderboards, and other players can no longer see it. One thing stays public as long as the name is yours: that it is taken, together with the internal user ID it belongs to, so that nobody else can claim it. Players who follow you keep your player name in their own list. Your email address is never shown to anyone.

Every public profile has a Report this name button. A report stores who reported, which name and account, the reason chosen, an optional note of up to 500 characters, and the time. Only we can read reports. We use them to rename or block names that break the rules.

Account data is stored in Cloud Firestore in Google's Frankfurt region (europe-west3). Firebase Authentication is a global Google service and may process sign-in data outside the EU, including in the USA; for that, Google relies on the EU-US Data Privacy Framework and the EU standard contractual clauses. Google processes this data on our behalf. More at https://firebase.google.com/support/privacy.

The legal basis for the account and syncing is the contract you enter by creating the account (Art. 6(1)(b) GDPR). A public profile is your choice and rests on your consent (Art. 6(1)(a) GDPR); you withdraw it by making the profile private. Reports rest on our legitimate interest in keeping names on Solvarium free of abuse (Art. 6(1)(f) GDPR).

We keep account data as long as the account exists. Inactive accounts are not deleted automatically. You can delete your account yourself at any time at https://solvarium.app/account. After you confirm (with Google, or with your password), this deletes your progress, profile, leaderboard rows, follow list and player name, and last the sign-in itself, at once; we keep no backup copies. Reports you sent, or that concern your name, are not part of your account: we keep them until they are dealt with and delete them once they are no longer needed. You can also ask us by email to delete your account, or only some of its data. Step by step, also for the Android app: https://solvarium.app/account/delete.

Advertising on Solvarium

Solvarium's content pages (home, game pages, guides, about) show no ads. They carry only a tag naming our Google AdSense account, and the file https://solvarium.app/ads.txt lists the same account. Both only tell Google that the site is ours; they load nothing and set no cookie.

When advertising is active, the browser games show ads from Google AdSense through H5 Games Ads (the Ad Placement API). This is not switched on yet; the rest of this section describes what applies once it is:

  • a full-screen ad at a break in play, for example between two puzzles, no more often than in our apps
  • an optional rewarded ad that you start yourself, for example for a hint. You get the reward only if you watch the ad

To show and measure ads, Google sets cookies or similar identifiers in your browser and processes your IP address, information about your device and browser, and the page the ad appears on. Google (Google Ireland Limited, and Google LLC in the USA under the EU-US Data Privacy Framework) decides itself how it uses this data and is responsible for it.

In the EEA, the UK and Switzerland the game first shows a consent message from Google (AdSense "Privacy & messaging", certified under the IAB Transparency & Consent Framework). Personalised ads are shown only if you agree. If you do not, Google shows non-personalised ads, chosen by context such as the game and your rough location rather than by your history. If you also refuse storage on your device, Google shows limited ads without cookies.

You can change your choice at any time through the privacy settings that Google's message offers on the page, or by deleting the cookies for solvarium.app; the message then asks again. Your own Google ad settings are at https://myadcenter.google.com.

How Google uses information from sites that use its services: https://policies.google.com/technologies/partner-sites. How Google uses cookies in advertising: https://policies.google.com/technologies/ads.

The legal basis for personalised ads and for storing information on your device is your consent (Art. 6(1)(a) GDPR, § 25(1) TDDDG). Showing non-personalised or limited ads without that consent rests on our legitimate interest in paying for games that are free to play (Art. 6(1)(f) GDPR).

The games

Solvarium is also an app for Android (Solvarium on Google Play), and this page covers it too. The app shows the same games, so everything above about the games, the anonymous player ID, accounts and deleting them applies to it in the same way; a game the app opens from solvarium.app runs in a view with storage of its own, separate from your browser. The app adds two things. To keep the leaderboards fair, it can ask Google's Play Integrity API (through Firebase App Check) whether a request comes from the genuine app on a genuine device. And when advertising is switched on in the app, it shows ads from Google AdMob (the Google Mobile Ads SDK): to show and measure them, Google processes your device's advertising ID, your approximate location derived from your IP address, and information about your device and the ads you see; in the EEA, the UK and Switzerland Google asks for your consent first, as described above. You can reset or delete the advertising ID in your phone's settings. Our standalone puzzle apps on Google Play each have their own privacy policy, linked from their store listings.

Your rights

Under the GDPR you have the right of access (Art. 15), to rectification (Art. 16), to erasure (Art. 17), to restriction of processing (Art. 18), to data portability (Art. 20) and to object to processing (Art. 21). Where processing rests on your consent, you can withdraw it at any time, with effect for the future. You can delete your Solvarium account yourself at https://solvarium.app/account; for everything else, write to yannick@sequencode.dev. You may also complain to a data protection supervisory authority, for example the one where you live.

Contact

Yannick Krüssel
Siedlung 16
49744 Geeste
yannick@sequencode.dev