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About Sudoku

Sudoku is the world's most popular number puzzle, played by hundreds of millions of people in newspapers, apps, and online every single day. Despite its name sounding Japanese, Sudoku has mathematical roots in 18th-century Europe and was popularized globally in its modern form in the 1980s. The objective is elegantly simple: fill a 9×9 grid with digits 1 through 9 such that each row, each column, and each of the nine 3×3 subgrids contains every digit exactly once. No arithmetic is involved — Sudoku is pure logic. You don't add, multiply, or measure anything. You reason: if this row already contains digits 1, 2, 3, 4, 5, 6, 7, and 8, then the empty cell must be 9. If this 3×3 box already has a 7 in three of its cells, then the remaining six cells cannot contain 7. Layer these simple deductions across 81 cells and the puzzle reveals itself — or stubbornly resists, demanding ever more sophisticated techniques. Beginner players start with "naked singles" — cells where only one digit can possibly fit given the current state of the puzzle. Intermediate players use "hidden singles," where a digit can only go in one cell within a row, column, or box even if that cell has multiple possibilities. Advanced players employ "naked pairs," "X-wings," "swordfish," and "coloring" techniques that feel like mathematical magic once you see them snap into place. Our Sudoku features three difficulty levels. Easy puzzles are solved almost entirely with basic deductions. Medium requires occasional backtracking and multi-step logic chains. Hard puzzles are genuinely challenging and may require the kind of advanced techniques competitive Sudoku solvers study for years. The game includes a notes mode — tap any cell and enter multiple candidate digits — plus a hint system for when you're truly stuck. A timer tracks your solve time, which is the standard metric for Sudoku improvement. **Tips:** Start by scanning each 3×3 box for missing digits. Look for rows or columns with 7-8 filled digits first — they're easiest to complete. Use pencil marks (Notes mode) for hard puzzles. Never guess — every Sudoku has a logical solution.