Rules & basics
Start here — how each variant works, why the rules exist, and how to read a grid without the basic stuff getting in your way.
The rules of Hyper Sudoku
Hyper Sudoku — also known as Windoku — is classic Sudoku with four extra 3×3 regions overlaid on the grid. Each of the four hyper regions obeys the uniqueness rule.
4 min read
The rules of Sudoku X
Sudoku X — also called Diagonal Sudoku — is classic Sudoku with one extra rule: both diagonals must also contain each digit 1–9 exactly once.
4 min read
How to solve sudoku
A complete framework for solving sudoku — the four levels of techniques, when each one shows up, and how to know which to try next.
35 min read
How to Play Sudoku: The Complete Beginner's Guide
Learn the rules of Sudoku, the core solving moves, and the habits that take a beginner from confused to confident in a single afternoon.
4 min read