Sudoku

Classic 9×9 Sudoku in a single index.html file: no frameworks, no CDN, 100% offline. Every puzzle is genuinely generated from the seed, with a guaranteed unique solution and difficulty graded by the hardest logical technique required.

Supports the ?seed= URL parameter (same seed + level = same puzzle), pencil marks, honest hints with explanation (technique, row, column and value), undo/redo and a debug overlay with a uniqueness self-test.