Puzzles that are provably fair

Every puzzle here is checked by machine before you see it and thrown away if it fails — a second answer where one was promised, a step that can only be guessed, a word nobody wrote a clue for. Where a guarantee cannot honestly be made, the puzzle says which one and why. No accounts, and nothing you type leaves your device.

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Nothing is uploaded Puzzles are generated on your own machine, and your progress, word lists and names stay in your browser. There is no account, no leaderboard and no score to compare against anyone.

Today

Three puzzles chosen by the date rather than by a server. No streak, no score.

Daily ChallengeA number, a word and a pattern, the same for everybody whose calendar says today. Independent, playable in any order, gone tomorrow.No streak

Play

Each of these states what it guarantees, and the guarantee is checked before the puzzle reaches you.

SudokuFive difficulty bands measured from the techniques a puzzle actually needs, and hints that explain the deduction before showing the digit. MinesweeperEvery board verified solvable by reasoning alone. About a quarter of ordinary boards end in a coin flip; none of these do.No guessing NonogramsA picture hidden in the row and column clues, solvable line by line in three sizes. Logic GridsWork out who has what by crossing off what cannot be true. Every clue is load-bearing. Number ForgeReach the target from the tiles you are given. Targets are drawn from what the tiles can actually reach, so a route always exists. Mental Math ArenaTimed and untimed arithmetic across fourteen topics, with a review of everything you missed. Arithmetic CagesFill a Latin square so every outlined cage hits its target. Four sizes, four measured bands, and no board that needs a guess.No guessing Sum PathStep from start to finish collecting exactly the target. Exactly one route does it on every board, proven by exhaustive search.One route CodebreakerDeduce a hidden code from how wrong your guesses were — or solve a table where exactly one code fits every row.Proven tables Pattern DetectiveWhat comes next, without the guesswork. Sequences are discarded when two known rules fit but disagree — and the wrong answers come from real misreadings.No ambiguity Memory GridA pattern appears, then goes. Put it back — or the order it came in, or the mirror of half of it. No score, no claims.No score kept CryptogramsSubstitution ciphers over lines written for the puzzle — no quotation is scraped and nothing is misattributed.Original lines

Arcade

Six originals rather than clones, each built around one idea the genre usually gets wrong — and each saying on the page what it does differently. Keyboard or touch, nothing to install, nothing to sign up for. All six, and what makes each one its own game →

Maze ChaseClear the dots and dodge four chasers that each hunt differently, then turn the tables with a power pellet.Arcade Asteroid DriftThrust, turn and break every rock in a field that wraps at the edges — with a blink that always lands you somewhere clear.Arcade Invader DropHold the line against a formation that marches faster with every one you take down, from behind bunkers that wear away.Arcade Brick ReboundA paddle, a ball and a wall — where it lands on the paddle decides where it goes, and the rally can never go flat.Arcade Bomber RunFly against waves of fighters and bombers — with a hitbox you can see, nothing arriving behind you, and no shot you could not have dodged.Arcade Kitchen LineSingles pickleball with the two rules the sport is built on actually in it — the non-volley zone and the two-bounce rule — and a reason given for every fault.Arcade

Print

Generators for the classroom, the kitchen table or a long journey.

Sudoku GeneratorSheets of verified puzzles with answer keys on their own pages, reproducible from a seed. Maze GeneratorFour sizes with solutions on a separate page, each verified to have exactly one route through. Word Search GeneratorYour own word list, with every word checked to appear exactly once so the answer key is never wrong. Bingo CardsClassic 75-ball, plain numbers or your own phrases — every card in a set verified different from the rest. Math WorksheetsPrintable arithmetic across fourteen topics and four levels, with answer keys and no awkward remainders. Crossword GeneratorYour own answers and clues, arranged and numbered. Every letter run in the finished grid is checked to be one of your entries. Cryptogram SheetsSheets of ciphers with answer keys on their own page, three difficulty levels and your own line if you want one.

What "provably fair" actually means here

Most puzzle sites generate a grid and publish it. The interesting failures are the ones that look completely normal: a Sudoku with two valid answers plays exactly like a good one until someone fills it in correctly and is told they are wrong, and a word search whose random filler letters happen to spell one of its own words sends a solver to the wrong place with a straight face.

So nothing here is published on the strength of the algorithm that made it. Every puzzle is handed to an independent checker — one that sees only what you would see — and thrown away unless it passes. For Sudoku, nonograms, logic grids and arithmetic cages that means proving exactly one solution exists, which requires continuing the search after the first is found rather than stopping there. For Sum Path it means enumerating every route across the board. For mazes it means checking the passages form a tree, for minesweeper that the board can be cleared without a single guess, and for a crossword that every letter run in the finished grid is one of the entries you wrote a clue for.

And where a guarantee cannot honestly be made

It is stated instead of quietly dropped, because the alternative is telling somebody who reasoned correctly that they were wrong.

Pattern Detective cannot promise a unique continuation, since no finite list of numbers has one — a polynomial can be drawn through any terms and end anywhere. What it promises is that of the seven rules it knows, exactly one fits; a sequence where two of them fit and disagree is discarded.

Codebreaker promises truthful, consistent feedback while you probe a hidden code — not that each guess narrows things to one answer, which is not how the game works. Its constructed tables are different: there, exactly one code fits, proven by enumerating the whole code space, and the mode is refused outright on settings too large to enumerate.

Sum Path answers are short and fairly direct, because a long wandering route cannot be the only one reaching its total — around twenty thousand other routes share it on a 6 × 6 board. The page says so rather than leaving players wondering why they never need to double back.

Difficulty is measured, not guessed

The usual shortcut is to label a Sudoku by how many clues it has, which is very nearly meaningless — this generator has produced two puzzles with 31 clues each, one beginner and one easy. Instead a second solver works the way a person does, applying named techniques in order, and the band comes from the hardest one the puzzle genuinely requires.

Every difficulty label on this site says in a sentence what it means, because a label you cannot interpret is decoration.

No accounts, no streaks, nothing to lose

There is no sign-in, no daily streak to break, no leaderboard and no notification. Progress is kept in your browser so a half-finished puzzle is still there tomorrow, and clearing your browser data clears it. Nothing about how you play is transmitted anywhere.