How to Play Lattice

1. Objective

A word square is a crossword with no clues. The grid is five by five, every row is a word and every column is a word, ten different words in all, and nothing tells you what any of them are. A few tiles are given to start you off. Everything else you work out from the way the words cross.

Here is a finished grid. Read it across and read it down: the rows are CRIME, LEMON, INPUT, FALSE and FLYER, and the columns are CLIFF, RENAL, IMPLY, MOUSE and ENTER. The tinted tiles are the ones a board like this might hand you at the start.

That is the whole rule. No black squares, no clues, no word used twice. Each cell is fixed by its row and its column together, so a letter you are sure of in one direction is a letter you have earned in the other.

2. The Daily Grids

Three grids publish every day, graded by the rarest word each one is allowed to contain:

• Easy: everyday words, and the most given tiles. Free, and no account needed.
• Medium: one or two words you may have to reach for, and fewer tiles given.
• Difficult: the rarest words the list allows, and the fewest tiles given.

Medium and Difficult need an account, and they unlock by climbing: solving a grid opens the next one, that same day. Yesterday's solve does not open today's Medium, and an attempt that does not solve opens nothing.

You get one attempt at each grid. Everyone gets the same three grids on the same day, and the board carries a countdown to the next set. When a grid is finished, solved or not, the definitions of all ten words are shown, so a word you did not know is a small lesson rather than a wall.

3. Filling It

The board opens with its given tiles in place and the first row selected. Tap a row tab or a column tab to work on that line, type the word along it, and check the line. The tiles come back in one of four colours, and the colours never mean two things:

• Blue: given. It was there when the board opened, and it is right.
• Green: found. The right letter in the right cell, and yours for good.
• Amber: misplaced. That letter belongs to this word, but not in this cell.
• Brick: absent. The word does not contain that letter at all.

The first two are permanent. The last two last only until you retype the line. A green cell is pinned in both its lines: a letter you earn in a row is already in place for the column that crosses it, which is how the grid pays you back for every correct check.

Three controls:

• Check line: marks the selected line against its answer. Only a full line of five letters can be checked.
• Clear: empties what you have typed on the selected line. Green and given tiles stay.
• Give up: ends the attempt and reveals the grid. It counts as your one attempt.

4. Checks and Rating

The budget

You have six checks. Five correct lines turn all 25 tiles green, so a clean solve leaves exactly one to spare, and every check beyond the fifth is one you had to spend on a line that came back wrong. The board counts them for you.

A check is the scarce thing here, so it is never wasted on a slip: a misspelling or a word that is not in the list is refused, not counted. Run out of checks with cells still open and the grid reveals itself, recorded as unsolved, definitions still shown.

Rating and Streaks

Signed-in players are rated. Every player starts at 1500, and each rung is itself rated, so the three grids are not worth the same: Difficult is a stronger opponent than Easy, and beating it moves you further.

A day counts towards your streak as soon as you solve any one of its grids; you do not have to clear all three. A day you have not played yet does not break it, because that grid is still open.

Your rating ranks you on the Lattice leaderboard, and feeds the one Overall rating BattleGuess keeps for you across every game you play. Guests can play Easy every day, but only signed-in players are rated. For questions, contact .

5. Where the Word Square Comes From

The word square is the oldest word puzzle there is. The Sator Square, five Latin words that read the same across and down, was scratched into a wall in Pompeii before the eruption of 79 AD, and copies of it turn up across the Roman world for centuries afterwards. Its five words, SATOR, AREPO, TENET, OPERA and ROTAS, still make a perfect five by five square today.

A square whose columns repeat its rows is the easy form, because you only have to find five words. The Victorian puzzle setters who revived the idea called the harder version a double word square: the columns are different words from the rows, so all ten have to be earned. That is the form Lattice publishes, and it is why no row on the board can ever be read off from a column.

What a daily version adds is the grading and the budget: a rung to climb once you solve, a rarest word each rung is allowed, and six checks to do it in.

6. Tips

• Read the given tiles as words, not letters. A row with three tiles given usually has one or two words that fit, and the columns crossing it will rule out the rest.
• Check the line you are surest of first. Every green pins a cell in the crossing line as well, so the first correct check makes the second one easier.
• Treat amber as information. A misplaced letter tells you the word contains it; slide it to the cell the crossing word allows.
• Count before you spend. The sixth check is the only spare. If a line could be one of two words, check a crossing line instead and let the grid decide.
• Play Easy first. It is free, it unlocks Medium for the day, and it starts the streak.