Privacy
Last updated 7 October 2026
Short version: LayerSudoku runs entirely in your browser. There are no accounts, and the game itself sets no cookies and tracks nothing. What it keeps is your own progress and settings, saved in your browser's storage on your device, and you can switch that off below. The site may show ads from Google AdSense. Google uses cookies to serve and measure those ads, as explained under Advertising.
What is stored, and where
When saving is on, the game uses your browser's local storage on this device (not cookies). It never leaves your device, it is not shared with us or anyone else, and other websites can't read it. Here is everything it keeps:
| What | Why |
|---|---|
| Settings (theme, highlighting, sounds, keypad and similar options) | So the game looks and behaves the way you set it. |
| The puzzle you are working on, with your digits, pencil marks, colours, notes, pen marks and timer | So you can close the page and carry on later. |
| Your progress on library and training puzzles (in progress / solved, time), and each one's board | So the front page can show your progress and let you switch between puzzles. |
| Your colour palette and your Quick puzzle choices | So they are remembered. |
If you turn saving off: a single entry, layersudoku.storage = off | So the site remembers your choice not to save anything. Without it, saving would turn back on at every visit. |
All entries except the last start with 3doku. (the game's earlier working name). Nothing in them identifies you.
Does the site work without storage?
Yes. Everything works with saving switched off, or in a private window. The difference is that your progress lives only in the open page: reloading or closing the tab loses it. To keep a puzzle without storage, use Share / Import to copy a puzzle code (with progress), or Export to download it as a file, and paste or open it again later.
Turning storage off
Untick Save my progress and settings in this browser above, or in the game's Settings → Privacy & storage. This deletes everything the game has saved on this device and stops it saving anything more. Only the one "off" entry described above is kept. You can turn saving back on at any time. You can also delete the saved data without turning saving off: the game then starts afresh, and saves again as you play.
You can also clear it through your browser, by deleting the site's data in its privacy or site settings.
Advertising
To keep LayerSudoku free, we may show ads through Google AdSense. When ads are shown, the pages load ad code from Google. Google and its partners (third-party vendors) then use cookies and similar technologies to show ads, limit how often you see the same ad, measure performance, and prevent fraud. That can include ads based on your visits to this and other websites ("personalised ads").
- Google's use of advertising cookies enables it and its partners to serve ads based on your visits to this and other sites. You can read how Google uses information from sites that use its services.
- You can turn off personalised ads from Google in Google's Ads Settings, and from many other vendors at aboutads.info (or youronlinechoices.eu in Europe).
- If you are in the European Economic Area, the UK or Switzerland, you will be asked for your consent before personalised ads or advertising cookies are used, and you can change your choice at any time. Without consent, Google may still show non-personalised ads, which use cookies only for things like frequency capping, measurement and fraud prevention.
The puzzles, your progress and everything you type never go to Google or to us. The ad cookies are set and read by Google, not by the game. The storage switch above controls only the game's own saved data, not advertising cookies: use the consent choices and links above, or your browser's cookie settings, for those.
Sharing and exporting
Puzzle codes, share links and exported files contain only the puzzle you chose to share (title, author name if you entered one, clues, and optionally the solution and your progress). They are created on your device and only go where you send them. In a share link the puzzle sits after the #, a part of the address that browsers never send to the web server.
Hosting
Like any website, the server that delivers the site's files may keep standard technical logs, such as IP address, time and the file requested, to deliver and protect the service. We don't use them to identify or track you, and the game itself sends nothing to the server while you play. Advertising is the one exception, as described above.
Children
The game collects no personal information from anyone. The site is not directed at children under 13. Ads are not personalised for users known to be children.
Changes and contact
If this policy changes, the date at the top will change too. Questions: [contact email], or ask on our Discord.