Learn the rule.
Then learn the rhythm.
Sudoku is a sequence of visible deductions. This library is designed to move a first-time player from the three classic rules to a reliable, no-guess solving routine.
Sudoku rules
The classic 9×9 contract in one clear page: digits, rows, columns, boxes, and why arithmetic is irrelevant.
Read the rules →02 / First solveHow to play
A two-step walkthrough: find a forced placement, then use row–column–box elimination to prove it.
Follow the walkthrough →03 / The ladderDifficulty levels
Understand Easy, Medium, Hard, Killer, and 16×16 Beyond without confusing format and difficulty.
Read the ladder →04 / CandidatesSudoku notes
Use candidate notes to preserve what is legal, reveal a forced move, and stop guessing.
Build a note routine →05 / Pattern workSudoku strategies
Move from naked singles to pairs, box-line interaction, and a careful introduction to X-Wing.
Study strategies →06 / MeaningSudoku meaning
Learn what the word means, how the Japanese name emerged, and why the rule is about logic rather than arithmetic.
Read the origin note →07 / Story routeDetective Sudoku
Understand the fictional Cipher detective and escape-room mood without mistaking it for a real case or a new rule set.
Explore the story route →A Sudoku board gives an answer when you remove every other answer.
The useful process stays compact: scan a nearly filled unit, list what is missing, test the crossing constraints, and place only the value that survives.
Start with a crowded unit.
When a row, column, or box contains most of its digits, its missing values form a small set. The intersecting lines remove possibilities until a single value remains.
See the walkthrough →