About Evil Sudoku
Evil Sudoku is the toughest difficulty on E-Sudoku. These fiendish 9x9 puzzles start with the fewest possible givens and demand the full range of solving techniques.
Reserved for seasoned solvers, an Evil puzzle can take a long time - but the satisfaction of cracking one is unmatched. Every board is still uniquely solvable by logic.
How to play Evil Sudoku
- Fill every empty cell with a digit so that each row contains the digits 1-9 with no repeats.
- Every column must also contain the digits 1-9 exactly once.
- Each of the nine 3x3 boxes must contain the digits 1-9 exactly once.
- Use the number pad or your keyboard to place a digit, and the Erase button to clear a mistake.
- The puzzle is solved when the whole grid is filled correctly.
Tips for Evil Sudoku
- Maintain meticulous candidate lists; Evil puzzles punish sloppiness.
- Combine advanced techniques: X-Wings, Swordfish, and coloring.
- Focus on chains of forced deductions rather than isolated cells.
- Patience is your best tool - take breaks and return refreshed.
Strategies and techniques for Evil Sudoku
X-Wing
When a digit is restricted to the same two columns across two rows (forming a rectangle), it can be eliminated from those columns in every other row. Rotate the idea for column-based X-Wings.
XY-Wing
Three cells with candidate pairs XY, XZ and YZ form a chain: the 'pivot' XY sees both others, so digit Z can be removed from any cell that sees both wing cells. A powerful tool for the hardest grids.
Swordfish
An extension of the X-Wing across three rows and three columns. When a digit's candidates line up in this pattern, it can be eliminated from the intersecting columns - essential for Evil-level puzzles.
Why play Evil Sudoku?
- Sharpens logical thinking - every move is a small deduction that trains your brain to reason step by step.
- Boosts concentration and patience, since a single puzzle rewards sustained, focused attention.
- Improves working memory as you hold candidate numbers and patterns in your head.
- A calm, screen-friendly way to relax while still giving your mind a real workout.