sudoku
The Complete Guide to Sudoku
How to play classic and Killer Sudoku, use candidates, apply solving strategies from singles to XY-Wing, and work through common questions when a puzzle feels stuck.
Sudoku Articles
Game-related articles are published here on games.homoonculus.com.
Articles
sudoku
The 45 Rule in Killer Sudoku — Innies, Outies, and a Worked Example
Every row, column and 3×3 box in a killer sudoku adds up to 45. This one fact turns cage sums into placed digits before any candidate work begins — here is why it holds, how innies and outies fall out of it, and a worked example you can check line by line.
sudoku
The History of Sudoku — Born in America, Named in Japan
The rules took shape in 1979 in the United States, the name and editorial culture flourished in 1980s Japan, and a British newspaper carried it worldwide in 2004 — Sudoku's journey across three stages, documented with sources.