Expert sudoku for experienced solvers
Expert sudoku is the hardest level on MindedGames. The starting grid is sparse, and after the usual pairs and X-Wings you will need XY-Wings, Swordfish patterns and forcing chains to make progress. Each puzzle still has exactly one solution reached by logic alone.
Play unlimited expert sudoku free in your browser, with pencil notes and undo. If you want a different challenge, try killer sudoku, where the cages add arithmetic to the logic.
What makes a sudoku expert?
Expert puzzles are built so that the usual techniques run out early. Progress depends on advanced patterns that connect several cells across the grid, and on keeping perfect pencil marks.
The techniques you need
- XY-Wing. Three cells with two candidates each, such as AB, BC and AC, where one cell sees the other two. Any cell that sees both of the outer cells cannot contain their shared digit.
- Swordfish. The three-row version of the X-Wing: a digit confined to the same three columns across three rows can be removed from the rest of those columns.
- Chains. Follow a chain of cells where each one being true or false forces the next. If both possibilities for a cell lead to the same conclusion, that conclusion is certain.
- Unique rectangles. Because a proper sudoku has only one solution, certain rectangular patterns of candidates are impossible, which removes candidates.
How experts work
Experts are methodical: they keep complete, accurate pencil marks, try the simpler techniques first, and only reach for chains when nothing else works. Short sessions help too; a fresh look often spots a pattern that ten tired minutes missed.
How to play here
Tap a cell and type a digit, or use the number pad on a phone. Right-click for pencil marks on a computer, or use Mark mode on a phone. If you want a new challenge after this, try Killer Sudoku on its hardest level.
How to play Expert Sudoku
- Fill every empty cell with a digit from 1 to 9.
- Each row, each column and each 3×3 box must contain every digit exactly once.
- The starting digits are fixed. Only the empty cells are yours to fill.
- Expert boards have a single solution that logic can reach, but the steps are long and rare.
Expert Sudoku tips
Learn XY-Wings and Swordfish
Expert boards often stall until a wing or a Swordfish pattern clears a key candidate. Look for them before anything more exotic.
Follow forcing chains
Take a cell with two candidates and follow what each choice forces. If both paths lead to the same result somewhere, that result is certain.
Work in short sessions
Expert puzzles can take an hour or more. Take a break when you stall. Fresh eyes spot patterns that tired ones miss.
Frequently asked questions
How is expert sudoku different from hard?
Expert puzzles use the same rules, but after the pairs and X-Wings run out they need rarer techniques such as XY-Wings, Swordfish and forcing chains.
Do expert sudoku puzzles have one solution?
Yes. Each expert board has exactly one solution. The logic is deep, but no guess is ever required.
Is there anything harder than expert?
The Size & level menu also has an Unreasonable setting. Those boards may need trial and error, so we keep them out of the expert page.
