In short
We do not collect personal data, we use no analytics or advertising, and we set no cookies. The site loads no third-party scripts, fonts or images.
What is stored in your browser
To let you continue a puzzle and keep statistics, the site writes to your browser’s local storage: saved games (the 30 most recent puzzles, with timers and undo history), statistics (puzzles played and solved, best and average times, day streaks), your game settings (sound, vibration, highlighting), the logbook of days on which you solved a daily puzzle, and your choice of paper or blueprint colours.
This data stays on your device. It is not sent anywhere, and we cannot see it.
How to delete it
Clear this site’s data in your browser settings — usually listed under cookies and site data. In a private window nothing is kept once you close it.
Server logs
Like every website, the servers that deliver these pages process technical data about each request — your IP address, the page requested and the browser type — in order to send the page and to protect the site against abuse. We do not use this data to identify visitors or to build profiles.
Questions
Write to [email protected].
Last updated: 27 October 2026