Privacy

There is no account, and your puzzle progress stays on your device.

What is stored on your device

Your progress on each board, your pencil marks, your elapsed time, and whether you have seen the one time welcome message. This is kept in your browser's local storage on the web, and in the app's own storage elsewhere. Clearing your browser data erases it, and it does not follow you between devices.

What leaves your device

The puzzles are made on your device from the date. The board itself never leaves, and neither do your pencil marks or your part-finished grid.

We do send a small count when a puzzle is put on your screen, and when you start, finish, or give up on one. It says which day and level, how long you took, and how far you got. That is all. It is described in full below.

The first of those is why: without it we cannot tell the difference between nobody visiting and people visiting and not playing, and those two need opposite fixes. It records the same two facts as the others, the day and the level, both of which are the same for everybody on a given day.

1. Sharing a result. Choosing share creates a link containing the day, the difficulty and your time. It never contains the board or its solution.
2. Opening a share link. Visiting a result page requests that page from our server, the same as visiting any web page.

What is not collected

No account, no email address, no name, no contacts, no location, and no cross site tracking profile. There is no login because there is nothing to log in to.

Standard server logs

This site is served by Cloudflare, which processes requests and keeps operational logs such as IP address and user agent for security and reliability. That is ordinary web hosting behaviour and is not used to build a profile of you.

What we count while you play

We count three things: that a puzzle was started, that one was finished, and that one was given up on. Each count carries the day number, the level, your time if you finished, and how many squares you had filled if you gave up.

It answers three questions and nothing else. How many people play. Whether the levels are honest, so Hard really is harder than Easy. And where people get stuck.

Your device also makes up a random string of letters and numbers the first time you play. It is not made from anything about you or your device. It is not your name, your email, your location, or anything a phone knows about you, and it cannot be turned back into any of those. It lets us see whether somebody came back the next day. Nothing more.

Clearing your browser data deletes it, and the next visit makes a fresh one. So there is no way to join up what you did before and after.

If your browser sends Do Not Track or Global Privacy Control, we do not attach that random string at all. You can also turn it off in the app. In both cases the puzzle count still happens, because that is a fact about the board rather than about you, and the random string is simply left out.

We do not use Google Analytics or any other outside company for this. The counts go to our own server and stay there for three months.

Advertising

The web version carries ads, and the provider is Google AdSense. The iPhone and Android apps carry ads too, and the provider there is Google AdMob. Google may set cookies or read a device identifier to choose and measure the ads you see. We never send Google your puzzles, your times, or anything you type into a board.

In the iPhone and Android apps, ads are requested as non-personalized. The apps do not ask to track you across other companies' apps and websites, and they request no permissions at all.

You can remove the ads in the iPhone and Android apps with a one-off purchase, made through Apple or Google rather than through us. We never see your payment details. The macOS and Windows apps are paid downloads and have never carried ads.

You can review how Google uses information from sites that use its services, and change your Google ad settings at My Ad Center.

On the web, if you are in the European Economic Area, the United Kingdom or Switzerland, you will be asked before any advertising cookie is set. You can accept, refuse, or open the options and choose in detail. Refusing is offered at the first screen, not buried a level down. You can change your answer at any time.

The game itself never needs an ad to work. Every puzzle is fully playable whether ads run or not.

Children

The game asks for no personal information from anyone, of any age.

Contact

Questions about this policy can be sent to the address listed on the thanks page.