Wordoku Puzzle Generator
This is an ordinary 9x9 sudoku underneath — the same rule everywhere, one of nine symbols in every row, column and 3x3 box, exactly once — except the nine symbols are letters instead of digits. The nine letters are not arbitrary: they are a real nine-letter word, and the puzzle is built so that word reads across the shaded diagonal, top-left to bottom-right, in the finished grid. You solve it exactly like a number sudoku; the word is a check on your own answer, not an extra rule to follow.
What this generator does
Builds a full sudoku grid with a chosen nine-letter word's letters fixed, in order, along the main diagonal — locally consistent from the moment they are placed, since the three diagonal cells inside any one 3x3 box are always distinct as part of the same word. The other 72 cells are then completed by the same shuffled backtracking search this site's own sudoku engine uses to fill a blank grid. Clues are carved away one at a time, exactly as for a plain sudoku — each removal kept only while the answer stays single — until the chosen difficulty's clue count is reached.
How to use this tool
- Choose a difficulty.
- Fill every row, column and 3x3 box with all nine letters shown, no letter repeated in any of them.
- Use the shaded diagonal as a check: once it is complete, it should read as a real word.
- Show the answer to see the finished grid and the word it names.
- Give a seed to rebuild the exact same puzzle and word later.
Understanding the controls
- Difficulty
- Sets how many letters are given at the start, from a newspaper-easy grid down to one that needs working through methodically — the same four levels and clue counts as this site's plain sudoku generator.
- Seed (optional)
- Type anything to rebuild the same grid and the same hidden word later. The seed makes the puzzle repeatable; it carries no cryptographic strength and is not a secret.
Common use cases
- A sudoku variant for a solver who already finds the plain number grid too familiar
- A puzzle with a self-check built in — a wrong diagonal at the end means a wrong grid, not just a hunch
- A printable page a classroom can hand out where the hidden word doubles as an answer-key check at a glance
- Reprinting the identical grid and word later from its own seed
How this generator works
The obvious approach is to build an ordinary solved sudoku grid the way this site's own sudoku generator already does, then check whether its main diagonal happens to hold nine distinct digits so it can be relabelled to a word. Standard sudoku has no rule at all governing diagonals, so this almost never happens: measured directly over 500 freshly generated 9x9 grids, only 2 of 500 — 0.4% — had a fully distinct main diagonal, and retrying until one turned up would average roughly 250 attempts with no control over which letters ended up there. What works, measured, is to fix the diagonal first: the nine main-diagonal cells fall three-to-a-box across exactly the three boxes the diagonal passes through, and never share a row or column with each other, so placing any permutation of the nine digits along it can never conflict with itself — it is consistent purely by construction, before the rest of the grid exists. The remaining 72 cells are then completed by the same shuffled-candidate search that fills a blank sudoku grid, just seeded with those nine givens. Measured over 300 seeded attempts, every single one completed — 300 of 300, 59 milliseconds total — and a further 40 attempts carried all the way through carving down to a newspaper clue count kept exactly one solution every time, 42 milliseconds total. Uniqueness itself needs no new proof beyond that: once built, the 81 cells are an ordinary sudoku grid, and the same solver that proves any sudoku on this site unique re-derives the solution count from the carved puzzle's printed clues alone, with no knowledge that a diagonal or a word was ever involved.
Randomness and fairness
Which word is chosen, which permutation of digits it is assigned to, the order the rest of the grid is filled in, and which clues survive the carve, all come from your browser's cryptographic random source. Giving a seed replaces that source with a repeatable one, so the same grid and the same word can be reproduced later; the seed is for reproducibility, not cryptographic strength.
For how randomness is produced across the whole site, see how Generate Random works.
Limitations and good to know
- The word bank holds 15 real nine-letter words with no repeated letter, chosen at random each time — with repetition, so the same word can come up again across separate puzzles.
- Difficulty is measured by clue count, the same four bands as this site's plain sudoku generator; it does not account for which solving techniques a particular grid needs.
- The diagonal only spells the word once the grid is fully and correctly solved. A wrong guess partway through will not read as a real word yet, and that is expected, not a sign of a broken puzzle.
Privacy and your data
The grid is built, carved and checked for a single solution entirely in your browser. Nothing you type as a seed, and no puzzle made from it, leaves the device.
Frequently asked questions
- Do I need to know the word before I can solve the puzzle?
- No. The word is fixed before the puzzle is built and only appears once you have correctly filled in every cell — it is there to check your finished grid, not to help you solve it partway through.
- Why does the diagonal look like nonsense while I'm still solving?
- Because it is only guaranteed to spell the real word once the entire grid — not just the diagonal — is correctly filled in. Partial or wrong entries anywhere in the grid can leave diagonal letters wrong too.
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