Play Hard Sudoku Online - Free
Hard Sudoku assumes you keep clean pencil marks and read interactions between boxes and lines. Expect locked candidates, claiming, and naked or hidden triples - patterns that eliminate candidates rather than immediately place digits. A hard puzzle rewards patience: one good elimination often unlocks a chain of easy placements right after. Solved regularly, this level turns intermediate players into strong ones.
Techniques you'll need
- PointingA box confines a candidate to one row or column.
- ClaimingA row or column confines a candidate to one box.
- Naked TripleWhen three cells in a unit share only three candidates.