If you can handle any puzzle with ease and want to get through a difficult level, then Devil's Sudoku is a great option. It's not enough to know the basic rules and solution methods. You need to be familiar with unconventional methods, be able to use them at the right moment, and have a lot of experience with the game.

At first glance, this is a very ordinary puzzle, consisting of a 9×9 square with a set of one-digit numbers from 1 to 9. But it can be solved only by an experienced professional who has not only learned the basics of Sudoku, but has also spent a lot of time solving logical problems.

## What is the difference between Devil's Sudoku and ordinary Sudoku?

Devil's Sudoku is a variation of the classic game with increased complexity. The rules of the game remain the same: place numbers from 1 to 9 in empty cells so that there is no repetition in separate blocks 3×3 and in vertical and horizontal rows.

The main difference of the Devil's level is the minimum number of filled cells in blocks: maximum 4, more often 3 or 2. To solve such a puzzle you need to show maximum flexibility of mind and know certain techniques and strategies.

## Some tips for solving Devil's Sudoku

The following rules should be followed to solve the puzzle:

- Start with 3×3 blocks that contain more cells. They are easier to solve.
- Remember your own methods and strategies for solving sudoku and try to put them into practice.
- Concentrate on the game.

## The main method for solving Devil's Sudoku

Without experience in the game and knowledge of strategies, the Devil level cannot be passed. Even if the player can easily solve simple sudoku variants, solving the advanced level is not so easy.

Among the methods and strategies, the most popular and effective is the "XY-wing" method.

## The rules of the "XY-wing" method

The essence of the "XY-wing" method is the exclusion of digits. Let's take 3 connected blocks, in each of which we will insert 2 possible digits. The central block will be the "trunk" and the side blocks will be the "branches". According to the rules, each block can have only 1 out of 3 digits. Let's name them alphabetically: X, Y, Z. Accordingly, the letters can stand for any 3 numbers.

The candidate numbers XY are in the "stem" block. XZ and YZ are in the "branch" block. Logically, the candidate number Z cannot be in a cell that has a common row and column and goes through the stem and branches at the same time. This conclusion automatically says that Z is excluded.

## Why it's useful to solve the Devil's Sudoku

Sudoku has a great influence on mental development and trains the brain. Solving devilish puzzles improves the following skills

- Logical thinking training;
- Memory development;
- The ability to make quick decisions in unusual situations;
- Improvement of concentration;
- Development of analytical abilities.

Systematic solving of complex Sudoku puzzles will help you not only to easily overcome difficulties in the game, but also to develop and accelerate thinking processes for solving difficult problems in real life.