Eight guides, ordered from the rules through to the techniques that Expert grids demand. Each one is worked through with diagrams rather than described in the abstract — the patterns are much easier to recognise than to read about.
The rule, the vocabulary, and how to read a cell's candidates. Start here if you've never finished a grid.
The no-pencil-marks technique that fills most of an easy grid, and how to tell when it has run out.
The two kinds of forced cell. Hidden singles are the ones beginners walk straight past.
Your first real eliminations. Pairs don't place digits — they clear the way for the ones that do.
Locked candidates: what happens when a digit is confined to the strip where a box and a line overlap.
Four cells, four units, one rectangle. Why the eliminations hold even though you never learn which diagonal is right.
Why clue count is a poor guide to difficulty, and exactly which techniques Easy, Medium, Hard and Expert each require.
Speed comes from wasting fewer passes and making fewer mistakes, not from thinking faster.