Mountain StreamLast updated 5 September 2026
Mountain Stream Playground, at playground.mountainstream.dev, hosts our browser games and links out to our other projects. It has no accounts, no cookies, no advertising, and no tracking across other sites. This page describes the little it does store. Linked projects on their own addresses — such as Sol Lä-get — carry their own privacy pages.
On your device
Your game progress — the current board or drawing, timer, settings, levels completed, and a copy of the current level list — is saved in your browser's local storage. It stays on your device. We cannot read it, and it is never sent anywhere except as described below. Clearing your browser's site data removes it.
What our servers receive
- When a game asks for a new puzzle, the request carries the chosen size and difficulty, together with the random identifiers of puzzles you have already completed, so a fresh one comes back. These identifiers name puzzles, not people, and are not linked to you.
- Aqueduct fetches its level list from our server when it loads, so new levels can appear without an update. The request carries nothing about you.
- The Aqueduct owner portal can save editor drafts of unpublished levels and daily-route choices. These are the owner's own work data, not player data, and are available only after owner sign-in.
- Owner sign-in, here and on portal.mountainstream.dev, runs through Google via Firebase Authentication. The sign-in state stays in that browser, and the only thing we read from it is the account's e-mail address, to decide which portals to show and to check owner access on the server.
- We count how often puzzles and levels are started, solved or failed, and how often hints are used — per day and per puzzle size, difficulty or level — along with game page views, how long solves take in coarse time bands, star ratings earned, how many Journey and daily-route runs start and how far they get (in coarse bands of levels), and the domain of the site a visit arrived from (the domain only, never the full address). These are plain totals with no identifier of any kind attached.
- If you mark a level as impossible, we receive the level, the reason you picked from a fixed list, your current drawing as coordinates, and how far the water got. Nothing you type is sent.
- If a game hits an error in your browser, it may send us the error message, the file and line it came from, the level in play, and the game's version number, so we can fix it. No identifier, browser details, or page address is included, and only a handful of reports are sent per visit.
- Like almost every web server, ours keeps standard access logs (including IP addresses) for up to 30 days to operate the service and defend it against abuse. The servers run on Google Cloud in the European Union.
Legal basis
Where the GDPR applies, we process the above under legitimate interest (Art. 6(1)(f)): operating the games, keeping them working, and understanding — in aggregate — how they are played. We store no personal data beyond the transient server logs.
Your rights
Under the GDPR you can ask what data we hold about you, and ask for it to be corrected or deleted. Since we keep no personal data beyond short-lived server logs, there is usually nothing to retrieve, but you are welcome to ask. You also have the right to complain to your data protection authority — in Sweden, IMY.
Contact
Mountain Stream Studios AB · Org.nr 559445-4752 · Gothenburg, Sweden
jonatan@mountainstream.dev
Changes
If what we store changes, this page changes with it, along with the date at the top.