How Tidy Puzzles works

Every puzzle on this site is generated on your device from a seed, which is why dailies are identical for everyone, why a five-letter code can replay any puzzle, and why the games work offline. This page explains the generators, what each game guarantees, and what we do and do not keep about you.

Puzzles are generated on your device

There is no server handing out puzzles. Each game ships its own generator, and the generator is deterministic: give it the same seed and it produces the same puzzle every time, on any device. The random numbers come from a seeded generator (the seedrandom library), so a random puzzle is reproducible whenever we want it to be.

Seeds and puzzle codes

When you press New game, the shell draws a random seed and shows it as a short code such as Puzzle #A7K3Q. The code uses 32 characters without 0, O, 1 or I so it can be read aloud or typed from a photo. Type a code into the same page, or open the page link with the code attached, and you get the identical puzzle, which makes it easy to race a friend or ask for help with a specific grid. A code belongs to the game and variant it was made on; the same letters on a different variant produce a different puzzle.

Daily puzzles

A daily's seed is the date in UTC plus the game's id. That is the whole trick: nobody has to download the day's puzzle, everyone computes the same one, and it changes at midnight UTC. Sudoku, Minesweeper, Solitaire, FreeCell and Nonogram have dailies, and the last 30 days are kept in an archive on each daily page.

What each game guarantees

A generated puzzle is only worth solving if it is fair. These are the checks that run before you see a board.

Sudoku: exactly one solution, rated by technique

The generator fills a valid grid, then removes clues one at a time while a counting solver confirms the solution is still unique. The finished puzzle is then solved again by a solver that only uses human techniques, and the hardest technique it needed sets the level.

• Easy: singles only; 36 to 45 clues.
• Medium: adds hidden singles and pointing pairs; 30 to 35 clues.
• Hard: adds naked and hidden pairs and triples, and box-line reductions; 26 to 30 clues.
• Expert: adds X-wing, Y-wing and swordfish; 24 to 27 clues.
• Evil: needs chains or a guess beyond those techniques; 22 to 25 clues.

Nonograms: solvable by logic alone

A random picture with 55 to 65 percent of its cells filled is generated, then run through a line-logic solver, the kind that only looks at one row or column at a time. If the solver cannot finish it without guessing, the picture is thrown away and another is generated. Every nonogram you see, including the daily 15×15, passed that test.

Minesweeper: a safe, useful first click

Mines are placed after your first click, so it never hits a mine and always opens a region of zeros. Mine counts are exact for each level: 10 on Beginner, 40 on Intermediate, 99 on Expert.

Sliding Puzzle and Lights Out: always solvable

Half of all random tile arrangements of a sliding puzzle cannot be solved, so we never shuffle at random. The board starts solved and is scrambled by playing real moves, which means the same moves in reverse solve it. Lights Out works the same way: the start state is made by pressing random lights, so a solution is known to exist and can be replayed when you finish.

Solitaire and Kakuro: winnable when we say so

Klondike deals come from a seed, and a seeded solver tries to complete each one. A deal is labelled winnable only when the solver has verified it; otherwise it is labelled as not guaranteed. FreeCell deals come only from a verified solvable range. Kakuro grids, like Sudoku, are generated with a unique solution.

Hints, undo and the timer

Every game defines its own hint: Sudoku names the next logical cell and the technique that finds it; Minesweeper points to a safe cell; Solitaire highlights a legal, productive move; a nonogram hint points to one determinable cell; Word Search flashes the first letter of a word. The first two hints in a puzzle are always free. If rewarded ads are switched on, later hints offer a choice: watch a short ad or wait 30 seconds. There is never a hard wall, and pages for children never show that prompt.

Undo is unlimited in the puzzle games and the card games, and one step in 2048. The timer starts on your first move, pauses when the tab loses focus or you press Pause, and the board is hidden while paused so a daily time cannot be gamed.

What we keep and what we do not

Stats live in your browser

Your unfinished games, settings and stats (played, won, win rate, best and average time, streaks) are stored in the browser using local storage and IndexedDB. They never leave the device. There are no accounts, so there is nothing to sync and nothing to breach; the cost is that a new browser starts from zero.

Analytics and ads

We use cookieless, aggregate analytics to see which games are played. Optional event analytics, when enabled, records only game ids, difficulties and outcome buckets, never anything about you, and only after consent where consent is required. Ads, when enabled, appear beside or below the board and at natural breaks: never before you can play and never over the board. The privacy page has the full detail.

Offline after the first visit

A service worker caches the site and every game on your first visit. After that, any page you have opened works without a connection, and because dailies are computed locally, so does today's daily for every game. Ads and analytics simply do not load offline.

Keyboard and screen readers

Every board is a grid of focusable cells with a label that says its row, column and state. Arrows move, digits and Enter act, F flags, N toggles notes, U undoes, H asks for a hint, P pauses. There is a high-contrast theme, a colour-blind palette for each game, and animations respect the reduced-motion setting. A screen reader gets a summary of the board on request.

Last updated 2026-09-27.