Solver Guide
If you can handle easy and medium sudoku but keep stalling on expert boards, the main shift is usually process. Evil sudoku becomes much more manageable when you move from guessy play into disciplined candidate tracking and technique-based elimination.
Use the main game to apply the guide immediately, or open the 17 clue page if you want an even sparser challenge.
Scan rows, columns, and boxes for the easiest placements first. The goal is not to solve a large part of the puzzle right away. It is to collect reliable information and avoid introducing mistakes early.
On evil sudoku boards, notes are not optional. They are the working memory of your solve. When the board stops yielding direct placements, accurate candidates make every later technique easier to spot.
Before reaching for complex patterns, make sure you have exhausted simpler logic: locked candidates, naked pairs, hidden pairs, and subset cleanup. Many evil boards open just enough after this stage for one or two strong eliminations to matter.
When the board is stable but crowded, that is the usual sign to look for higher-order patterns.
These patterns help you eliminate candidates without guessing, which is exactly what makes them so important for hard and evil sudoku.
Most hard solves are cyclical. A single advanced elimination often creates a new simple placement. After every breakthrough, return to easier scanning before looking for the next advanced move.