Terminology
Evil Sudoku Is This Site's Expert Difficulty
"Evil" is the name some Sudoku publishers give their hardest tier. This site calls the same tier Expert — 20 to 24 given clues, needing chain-based techniques. The puzzle itself is identical regardless of the label; only the name differs.
At a glance
Evil / Expert Sudoku at a Glance
- Also called
- Evil, Extreme, Master (by other publishers)
- On this site
- Expert
- Grid size
- 9×9
- Given clues
- 20–24
- Typical solve time
- 40–60 min
- Techniques required
- colouring, X-Chain, AIC, forcing chains, almost-locked sets
Naming
Why the Names Differ Between Sites
There is no industry standard for Sudoku difficulty labels. Newspaper puzzle pages and other generators use Evil, Extreme, or Master where this site uses Expert — the underlying clue count and required solving techniques are what actually determine difficulty, not the word chosen to describe it.
See how all difficulty levels are calibrated or read about the techniques Expert-tier puzzles require.
Download
Get an Evil (Expert) Sudoku PDF
FAQ
Evil Sudoku — Frequently Asked Questions
What is Evil Sudoku?
Evil is the name some publishers — including several major newspaper puzzle pages — use for their hardest Sudoku tier. On this site the equivalent is Expert: 20 to 24 given clues, requiring chain-based techniques like colouring and X-Chain.
Is Evil Sudoku the same as Expert Sudoku?
In terms of clue count and required technique, yes — different publishers use Evil, Extreme, Master, or Expert for the same top difficulty band. There is no industry-standard cutoff; each site sets its own clue range for its hardest label.
Why do different Sudoku sites use different difficulty names?
There is no shared standard. Some use Easy/Medium/Hard/Expert, others add Evil, Extreme, or Master as a tier above or in place of Expert. Clue count and required technique are more reliable difficulty signals than the label itself.
Is there a difficulty harder than Evil?
Not in any meaningful, consistently-defined sense — Evil, Extreme, and Master all describe the same practical ceiling: puzzles built around chain logic and forcing patterns rather than pattern-matching techniques like X-Wing alone.