Expert Sudoku
Expert puzzles reward you for seeing the whole grid at once. The key patterns are fish: X-Wing and Swordfish.
Expert Sudoku needs X-Wing or Swordfish, patterns where one digit is locked into the same two or three columns across two or three rows. They remove candidates from other cells in those columns. Complete notes are essential.
How to use the board
- Tap a cell, then a digit. On a keyboard, use 1 to 9, Backspace to erase and the arrow keys to move.
- Turn Notes on to write small candidate digits. Press N on a keyboard.
- Hint finds a naked or hidden single and tells you which one it is.
- Your game is saved in this browser. Nothing is sent anywhere.
Why Expert feels different
Up to Hard, the patterns live inside a single row, column or box. At Expert the logic crosses the grid: a digit's positions in several rows decide what is allowed in several columns. Learn them with real positions: X-Wing and Swordfish.
How to hunt for fish
- Choose one digit and mark only its candidates on a mental or paper copy of the grid.
- Find rows where the digit has exactly two candidate cells (for X-Wing) or two or three (for Swordfish).
- See if those cells line up in the same two or three columns.
- If they do, the digit must sit in those columns inside those rows, so remove it from the rest of those columns.
Prepare before you try
Master triples and pointing pairs first. If you cannot see a fish by eye, enter the grid into the solver and use step by step. It will show you the pattern on the grid.
Frequently asked questions
Which techniques does Expert use?
X-Wing and Swordfish, plus everything easier.
What is a fish in Sudoku?
A pattern where one digit is limited to the same lines across several rows or columns. X-Wing is size two, Swordfish size three.
Do I need to guess at Expert?
No. Every Expert puzzle here is solvable by logic.