Sudoku
Fresh puzzles with a guaranteed unique solution, in three difficulties.
About this sudoku
Every puzzle is generated on the spot and verified to have exactly one solution โ clues are only removed while uniqueness survives, which is the property that separates real sudoku from guessing. Three difficulties (40, 32 and 26 clues), keyboard and tap input, a check that flags wrong cells in red only when asked, a reveal-cell hint for mercy, and best times per difficulty saved on this device.
Solving techniques, in the order to learn them
All sudoku technique is systematic elimination. Scanning first: pick a number, sweep its rows and columns, and place it where only one cell in a box remains โ this alone solves easy puzzles. Single candidates next: a cell whose row, column and box already contain eight numbers is forced. Medium puzzles yield to doing both exhaustively; hard puzzles add pairs โ two cells in a unit sharing the same two candidates exclude those numbers elsewhere โ and the pencil-marking habit that supports them. The honest rule the uniqueness guarantee earns: you never need to guess; a stuck position means an elimination is still hiding, usually in the box you've looked at least. The 9ร9 modern form was popularised from Japan in the 1980s (the name is roughly "single numbers"), conquered the world's newspapers in 2005, and runs on the same logical muscles as Minesweeper โ with no arithmetic required at all.
Frequently asked questions
Are these real sudoku puzzles?
Yes, in the strict sense: each is generated fresh and verified to have exactly one solution, so pure logic always suffices โ no guessing is ever required.
What do the difficulty levels mean?
Clue count: easy starts you with 40 filled cells, medium 32, hard 26. Fewer clues means longer elimination chains โ hard puzzles expect pair logic, not just scanning.
Does using check or hint spoil the game?
Check only marks wrong cells when you ask, and the hint reveals one cell of your choosing โ house rules decide the shame. Best times save per difficulty either way.
Is sudoku a maths game?
Not at all โ the digits are just nine distinct symbols; letters would work identically. It's pure constraint logic, which is why it exercises the same muscles as Minesweeper.