Questions
What we get asked
The rule, the floor, your data, playing offline. If your question is not here, the “How it works” page probably answers it.
Do I need to be good at sudoku?
No, but you do need to be able to read a grid. You never write a digit: you work out which ones are still needed. A game or two is enough to get the hang of it, and the tutorial is three screens long.
Why seventeen and not zero?
Because it has been proved: there is no 9×9 sudoku with sixteen clues and a single solution, and there are ones with seventeen. That is a result about sudoku itself, not a limit of this game. In practice, almost no grid gets that low.
Can I lose?
No. Nothing ends the game: a sealed cell lowers the ceiling you can still reach, but your score never drops and you can carry on as long as you like. The only ending is the one you choose by banking.
Does the game cheat in my favour?
No. A removal’s verdict is the result of counting solutions, not of a difficulty dial. An easy grid and a hard one come out of the same code; what separates them is the grid, not a decision made about you.
What do other people see when I share a result?
A score, a floor, and a run of squares telling the order of your moves — never their position. The pattern of hollowed cells is the solution to the problem: sharing it would hand the answer to anyone who has not played yet. The share is chronological by construction, and a test in the game proves it rather than promising it.
Do I need an account? A connection?
Neither. The game makes no network request, not even on the first launch: the engine and the fonts are served with the page. It works in flight mode, and your games stay on your device.
Are there ads or purchases?
Neither, and nothing that leads to them: no analytics, no tracker, no account to create. The site you are reading loads nothing from another host either.
What does it run on?
A browser, phones first, in portrait. You can install it from the browser if you want to, and it plays just as well without installing it.
Why are the clues so low-contrast?
Because a clue is material, not information to be read quickly. The only colour in the game is the one coming out of the cells you have opened: the more you hollow out, the brighter the grid. The score is seen before it is read.
Does everyone get the same daily grid?
Yes, and nobody hands it out. The game carries its own random-number generator, written to draw exactly the same numbers on every platform and in every version. The date is enough to find the grid again.
A grid is waiting
Take one out, see whether the light comes through.
The game opens in the browser. There is nothing to install and nothing to sign up for.