Daily Binary Puzzle

One grid a day, identical in every browser that opens it, at any size from 6×6 to 14×14. Today’s comes from today’s date and nothing else.

Your record

• —Current streak
• —Longest streak
• —Days played
• —Best time, this size

How the date makes the puzzle

This site has no server and keeps nothing about you, so there is nowhere for a puzzle of the day to be stored and handed out. It works the other way round instead: the date is the puzzle. The calendar day is turned into a number, that number drives every random choice the generator makes, and the same number therefore produces the same grid on every machine running the same code — in Auckland, in São Paulo, on a laptop that has never contacted this site at all.

That is worth being straight about, because it has a consequence a server-backed site would not have. Tomorrow’s puzzle already exists. Anybody willing to move their computer’s clock forward can play it, and there is no secret being kept. Pretending otherwise would be theatre, and the honesty buys something real in exchange: nothing has to be fetched, so the grid is on screen before a networked site would have finished asking permission.

It also makes the archive an archive rather than a list of dead links. Any past date can be rebuilt exactly, cell for cell, so a link to a day last March opens the grid people actually played that March.

The week has a shape

Difficulty follows the day, the way a crossword week does. Monday and Tuesday are easy, Wednesday and Thursday need counting, Friday and Saturday need a whole line analysed, and Sunday is the one that leans on the third rule. Dates are read in UTC, so everybody turns the page at the same moment rather than at their own midnight.

The point of a fixed ramp is that it gives every reader days that belong to them. A random difficulty each morning means somebody who is happy at the easy end gets a puzzle they can finish one day in four; a ramp means they get two, they know which two, and the harder days are there to grow into rather than to bounce off.

Size is a separate choice and does not touch difficulty. A 14×14 easy puzzle is a long puzzle, not a hard one: it asks for the same two ideas as the 6×6 and asks for them a hundred and sixty more times. Pick the size for how much time you have and the day for how much thinking you want.

What the streak counts, and where it lives

A day counts once you have finished any one size. Playing all five does not earn five days, and there is no ranking to climb — the streak is a record of showing up, which is the only thing a daily puzzle can honestly measure.

Hints do not break it. A hint here names the technique it used and links to the page that teaches it, so a reader who takes one has done the thing the site is for. Marking that as a failure would be punishing somebody for learning.

Everything is kept in your own browser’s local storage: streak, completion history, best time per size. None of it is transmitted, there is no account, and clearing site data for this domain erases it for good. That is the trade for a site with no login and no tracking, and it is stated here rather than buried in a policy.

Common questions

More Binary puzzle pages

• Binary puzzleUnlimited grids
• The rulesThree rules, in full
• How to solveA 6×6, worked
• TechniquesThe whole ladder
• Doubles and sandwichesTechnique — easy
• Counting a lineTechnique — medium
• Line analysisTechnique — hard
• Twin eliminationTechnique — expert
• The assumptionTechnique — refused
• Printable puzzlesFor paper
• Daily archiveEvery past day