Samurai Sudoku

Hard samurai sudoku

Hard puzzles have 80 to 119 givens. Every puzzle requires cross-grid deduction to complete. You won't be able to make meaningful progress on any single grid without pulling information from at least one other grid through the shared boxes.

At this difficulty, naked and hidden singles inside individual grids run out quickly. The real work happens in shared boxes, where you combine row/column/box constraints from both parent grids to narrow candidates. A candidate that looks fine from one grid's perspective might be blocked by the other grid.

Hard samurai also starts requiring naked pairs and pointing pairs within individual grids. If you're not comfortable with those techniques in regular sudoku, work through a few hard 9×9 puzzles first.

Typical solve time is 30 to 50 minutes. Expert adds longer deduction chains that cross multiple grids.