The term x-wing itself derives from the x-wing fighters in Star Wars. There is a relationship between the diagonally opposite squares, hence the “x” in x-wing. The x-wing techniqueĮssentially, this method uses the fact that in certain cases, there are only two possible ways of placing two numbers in four squares which form a rectangle. Whenever you solve a square, you must remove that number from the pencil marks in all other squares in the same row, column and block. With many advanced techniques, the key is to spot patterns within your pencil marks to eliminate possibilities within other squares.

Pencil marks are small numbers, usually written at the top of each unsolved square, listing all the possible values for that square. Here we present the techniques that will help you solve the hardest puzzles using only logic and no guesswork.įirst a couple of preliminary points: if you have ever completed any Fiendish or Super Fiendish Sudoku, you will be familiar with noting down candidates or pencil marks. Please be reassured that all Sudoku puzzles published in the Times are always solvable by logical means. So, as we increase the difficulty Super Fiendish, the time has come to present the essential techniques for solving the most difficult Sudoku puzzles. Many have welcomed the new challenge but some have asked for help. In November 2006, The Times introduced a new extreme level of Sudoku giving players a more difficult level of logic: Super Fiendish.

Advanced solving techniques As seen on Times Online in February 2007

Evil sudoku tips