Hard and Expert Sudoku
For experienced solvers: Hard and Expert puzzles that need real techniques, graded by the logic required rather than the number of clues.
▶ Play Hard Sudoku▶ Play Expert Sudoku
How Hard and Expert are graded
Every puzzle is solved step by step by a human-style solver, and its level is the hardest technique it needed:
- Hard – hidden pairs and triples, naked triples and the X-Wing.
- Expert – the XY-Wing, Swordfish and naked or hidden quads.
That is why a Hard puzzle can have as many starting numbers as a Medium one (both often around 28–32) and still be much tougher. No puzzle ever requires guessing or trial and error, and each has exactly one solution.
Tools for serious solving
- Pencil notes laid out in a fixed 3×3 pattern, so pairs and triples are easy to spot.
- Highlighting of the selected number across the grid.
- Unlimited undo and redo, with an optional limit of 3 mistakes if you like a challenge.
- A hint that names the technique and shows where it applies, instead of just revealing a digit.
- An optional timer and personal best times per level.
Learn the techniques
Our Sudoku strategies guide walks through pairs, the X-Wing and the XY-Wing with clear examples. The Daily Sudoku is a Medium puzzle if you want a shorter daily workout.
Frequently asked questions
What is the difference between Hard and Expert Sudoku?
Hard puzzles need techniques up to the X-Wing. Expert puzzles need at least one advanced pattern such as an XY-Wing, a Swordfish or a quad.
Do I have to guess in Expert Sudoku?
No. Every puzzle can be solved by logic alone. If you feel stuck, the hint names the next technique.
Can I turn off the red mistake marks?
Yes. Switch off “Show mistakes in red” in Settings for a purer challenge.