Sudoku Clan › Expert Sudoku
Expert Sudoku
Expert puzzles cannot be finished by placing digits alone. You have to remove candidates first, with pointing pairs and naked or hidden pairs. Fiendish goes further, with triples, X-Wings and Swordfish. Play an Expert puzzle here.
Play an expert Sudoku
| 2 | 9 | |||||||
| 9 | 6 | 4 | ||||||
| 1 | 5 | 7 | 2 | |||||
| 8 | 4 | |||||||
| 8 | 5 | 6 | 3 | |||||
| 5 | 9 | |||||||
| 1 | 9 | 4 | 5 | |||||
| 3 | 7 | 9 | ||||||
| 8 | 1 |
Expert puzzle. Turn on JavaScript to play it here, or open the game.
What makes a Sudoku expert level
Up to Hard, there is always a cell you can fill directly. An Expert puzzle has moments where there is not. Every remaining cell has two or more candidates, and every remaining digit has two or more places in each unit. The puzzle is not broken, and you do not need to guess. You need a move that removes a candidate without placing anything.
In Sudoku Clan, Expert puzzles need locked candidates, which are pointing pairs and box/line reduction, and some need a naked pair or a hidden pair. An Expert puzzle has at most four of these moments, and each removal is usually enough to reveal a single and get the puzzle moving again.
The top level, Fiendish, needs triples or patterns that span the whole board: the X-Wing, the XY-Wing and the Swordfish. Other sites call this level evil, extreme or diabolical. You can choose Fiendish in the game.
How to solve an expert Sudoku
- Take every direct placement first: hidden singles and naked singles.
- When you are stuck, fill in pencil marks for the whole board.
- Go through the boxes digit by digit. Wherever a digit's notes inside a box share one row or column, erase that digit from the rest of the line. Then do the same from the other side, from lines into boxes.
- Look for naked pairs: two cells in a unit with the same two notes. Then hidden pairs: two digits that appear in only the same two cells of a unit.
- After every removal, go back to step one. Advanced moves exist to uncover simple ones.
Accuracy beats speed
At this level one wrong note can cost you the puzzle, because a false pair looks exactly like a real one. Work in a fixed order and update notes after every placement. The target time for Expert is 22 minutes, and 34 for Fiendish, so there is no need to rush.
Put it to use
These techniques are worth points in Duel, the turn-based mode: a digit that needs pointing scores 2, a pair scores 3, a triple scores 5, and a wing or a fish scores 8, against 1 for a single. If you can see a pair that your opponent cannot, you win the match on a handful of moves.
Questions
What is the hardest level of Sudoku?
In Sudoku Clan the hardest level is Fiendish, which needs triples, X-Wings, XY-Wings or Swordfish. Other publishers use names like evil, extreme or diabolical for their top level.
What techniques do expert Sudoku puzzles need?
Pointing pairs and box/line reduction, and often a naked or hidden pair, on top of singles. Fiendish puzzles also need triples, X-Wing, XY-Wing or Swordfish.
Can expert Sudoku be solved without guessing?
Yes. Every Sudoku Clan puzzle is checked by a solver that uses only human techniques, so there is always a logical step available.