Codeword Puzzle Generator

Numbers instead of letters

The grid is filled with interlocking real words, and every distinct letter is mapped to a unique number from 1 to 26. White cells show the numbers; a handful of starter letters are revealed to give you a way in, and an A–Z strip down the side is where you record each letter as you crack it.

Set the grid size and how many starters you want, with an answer key if you need one.

No clues, and that is the point

A crossword gives you definitions. A codeword gives you nothing but the structure, so every deduction comes from the language itself.

You are not recalling facts. You are reasoning about which letters can plausibly sit where — which is a different pleasure, and it is why codewords suit people who bounce off general-knowledge crosswords.

How to break in

Start with the letter frequencies and the shapes.

The number appearing most often is very likely E, then T and A. A single-letter word is A or I. A three-letter word ending in the commonest number is probably THE. Any word with the same number in first and last position narrows sharply.

Then use the impossible combinations. Q is almost always followed by U, so a number pair that appears together and nowhere else is a strong candidate. No English word has more than three of the same letter running, and very few have a double letter at the start.

Cross the strip off as you go

The A–Z strip is not decoration and skipping it is why people stall.

Each letter is used exactly once, so eliminating one narrows every remaining number. Late in a puzzle the strip does more work than the grid — you will crack the last four cells by noticing that only J, Q, X and Z are left rather than by reading the words.

Starters

More starters, easier puzzle. It is the difficulty dial and it is a blunt one, so change it before you change the grid size.

A larger grid is not straightforwardly harder, incidentally: more words means more crossings, and more crossings means more constraints to reason from. A small grid with few starters can be the meaner sheet.

Who they suit

Anyone who likes sudoku but wants words. Language learners, since the reasoning is about letter patterns rather than vocabulary. Cover lessons and form time. And people who find crosswords unfair because they hinge on knowing a particular thing.

Related: cryptograms, which apply the same substitution idea to a sentence instead of a grid.