Sudoku

Classic 9×9, with technique-tier difficulty.

About

Classic 9×9 sudoku with constraint-deduction-only difficulty tiers — every puzzle is solvable without guessing. Tiers are assigned by the techniques required to solve: easy (naked/hidden singles), medium (pairs/pointing), hard (X-wing/triples), expert (swordfish, XY-wing, single backtrack). 100% unique-solution generation.

How to play

Fill every cell with a digit 1–9 so that each row, each column, and each of the nine 3×3 boxes contains every digit exactly once. Click a cell to select; type 1–9 to enter; type 0 or Backspace to clear. Givens are fixed and cannot be edited.

Features

• Technique-tier classification (easy / medium / hard / expert)
• 100% no-guess-required up through expert
• Constraint-propagation + backtracking solver
• 100% unique-solution acceptance
• Visible 3×3 box subdivisions
• Vanilla TypeScript, single-bundle build

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