Sudoku designers the world over will weep and gnash their teeth at the revelations in this comprehensive guide to cracking the addictive puzzles–but solvers will find it absolutely invaluable as they seek to improve their skills. Even experts don’t know all these tricks: hidden pairs, naked pairs, X-wings, jellyfish, squirmbag, bivalue and bilocation graphs, and chains, plus the exclusive Gordonian logic methods that turn the toughest puzzles into a breeze. There are hundreds of sudoku to practice on. A special addition is a reprint of the very first sudoku ever published!