How to play
Each answer has a crossword-style clue, and each answer is an anagram of those next to it with a letter added or removed.
The letters that stay also have to change places. REVEAL to LEAVE counts because the letters are rearranged. LEAVER to LEVER does not, because it only drops the A and leaves every other letter where it was.
Where a word has two spellings made of the same letters, either one is accepted. Otherwise the clue says which spelling it wants.
The games
There are nine games, and four are set each day. Every one of the nine comes round at least once in any three days.
Fold
Up or down as it pleases, a letter at a time.
Soufflé
The answers grow to a peak, then shrink back.
Flip
The answers take turns, one letter longer and then one letter shorter.
Roux
The same three letters sit in every answer.
Reduction
The letters that are taken away spell a hidden word.
Fork
The chain splits into two arms, which meet again at the same answer.
Double Yolk
Double Yolk is the exception to the rule that the other letters must move. Only one letter changes and the rest stay where they are, so every answer is the same length. Lewis Carroll invented this in 1877 and called it Doublets.
Scratch
The aim is to find words that get from the starting word to the ending word in the number of steps shown. Each step must be an anagram of the word before it with a letter added or removed. Steps that only add or drop a letter don't count. More than one route works, and the counter shows how many are still open.
Lattice
Every answer is one step from all the answers next to it, above, below and to either side.
Hints
You start with fifty hints in the app and five on the website, and you earn another for every puzzle you solve. They pile up and never expire, and a day never starts with fewer than three. Using a hint shows a letter of the answer you are on. Scratch has no clues, so there a hint shows a letter of a word that fits the box you are on, and asking again shows another letter of the same word.
There is no button that fills in the answers. On this website you can play today and the two days before it. The app keeps every day you open while it is free, so you can always come back to a game from that day.
Streaks
A day counts towards your streak once you have solved all four of its puzzles on the day itself, with or without hints.
Challenges
Share a day you have played, and the link you send is a challenge. Anyone who opens it can play the same puzzles. When they finish, they see your result beside theirs and can send theirs back.
Most puzzles solved wins, then fewest hints, then the quicker time.
How the keyboard helps
A letter goes dim on the keyboard when it cannot belong to the answer you are typing.
An answer is built from the letters of the one beside it, give or take one, so once you have a solved answer the keyboard knows how many letters the next or previous answer may hold, and what all or some of those letters must be.
When an answer requires an extra letter, any letter can be typed. Once a letter that is not in an adjacent answer is typed, though, the only letters left will be the ones from the adjacent answer and everything else goes dim. If a wrong letter dims the rest of the keyboard, delete it to bring the other letters back.
If there are two adjacent answers that have been solved, then the keyboard takes that into account as well. For example, if you are solving a clue and the answer before was BITE and the one after is TIED, the only letters available to you will be the five distinct letters from those words: B, D, E, I and T.
Double Yolk works a bit differently. Each answer differs from its neighbour by one letter, so once that one difference is on the board every remaining letter is settled.
On a computer keyboard, type the letters as you would anywhere else. Tab moves between answers, and Shift-Tab goes back. Press Escape to reach Hint and the other buttons, then Tab to move among them.
The anagram rack
This button, in the bar above the keyboard, opens a rack of letters to push about, the way you would on paper. It may automatically give you letters based on what's already solved in the puzzle. Type into it, or press Shuffle to mix the letters up. Drag a letter to move it, or tap two to swap them. Drag a key up onto the rack to put its letter where you drop it. Flick a letter up, or press Delete, to take one off. A letter the solved answers say must be there stays put.
The printable sheet
Any day on the site can be printed. The Print button sits under the day's puzzles on the front page, and the sheet carries the whole day on an A4 page or two: the clues, the tiles to write in, Roux's three letters, Reduction's margin, Fork's diagram and Lattice's grid.
New puzzles
New puzzles appear at 05:00 UTC. That is 3:00pm in Sydney, or 4:00pm while New South Wales is on daylight saving, 1:00pm in Perth, 5:00am in London, or 6:00am during British Summer Time, and midnight in New York, or 1:00am during US daylight time.
How the puzzles are made
The chains themselves are built by a program. It works through a dictionary of its own, finds the words that can follow one another under the rule for each game, and checks the day against the rules before the day is kept. The word list it draws on is published in full on the word list page.
The clues are set by a human: Aver, Omeletter's setter.
A clue that looks wrong
Report, in the toolbar, opens a short form with the date, the game and the clue already filled in. Say what is wrong with it and send. We read every report and correct the clue when it is wrong.
Starting again
Everything the website remembers about your play, which answers you have solved, how long they took and your streak, sits in this browser and nowhere else. Clearing it puts every day back to untouched, including the ones you have finished, and it cannot be undone from our end because we have no copy.
That also means your streak goes if you clear your browsing data, play in a private window, or move to another browser or another computer. There is no account to log back in to. The app keeps the same record in your own iCloud, so a streak built there survives a new phone.