Sudoku Guide

Sudoku means single number in Japanese, and the name hides the game's core rule. We trace its origin and real misspellings from our own search data.

Six dug girandola grids: a nine-cell pinwheel that replaces 3.5 givens, bans one digit from six cells at once, and passes once in 750 boards. Rules inside.

We dug six anti-knight grids to the bone: the knight-ban replaces 11 givens a puzzle and creates sudoku's oddest opening. Full rules, geometry, and numbers.

We dug six grids to the bone: with every edge carrying a greater-than sign, the puzzle drops from 24.7 cell clues to one on average. Rules and order of attack.

We dug six tested grids to their minimum: eighteen sandwich sums cut the clue count from 24.7 to 12.2 on average. Full rules, the zero-sum trick, and the math.

We generated six grids and dug each to its minimum: thermometers cut the clue count from 24 to 17 on average. Full thermo sudoku rules and window math inside.

We measured 224 real consecutive bars on 6 engine-generated puzzles: 80% pin a cell outright while the no-bar rule strips candidates. Full rules inside.

We generated 3 puzzles with our engine and measured the arrow rule on 54 real arrows. Here's how arrow sudoku works, with full grids and candidate math.

We generated 42 sudoku puzzles and tracked every technique our solver used. Here's what sudoku patterns actually solve games — and how to spot each one.

Learn the sudoku rules in 30 seconds, then see how the first moves of a real solve work: we generated 320 puzzles and logged every move our engine made.

We ran a strict singles-only sweep over 320 puzzles: most hidden singles hide in cells with 3+ candidates, and pointing pairs unlock 8 of 10 stalled evil grids.

Measured over 320 real solves: easy sudoku runs on a single 41-move naked-single chain, and even evil grids stay 61% singles before search takes over.