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Sudoku Variants

Beyond classic Sudoku lies a whole family of variants: extra diagonals, overlapping regions, arithmetic cages and giant interlocked grids. Same one-per-line spirit, brand-new logic. Here's how each one works.

• Diagonal Sudoku (X-Sudoku) — play freePlay diagonal Sudoku, also called X-Sudoku: classic rules plus both main diagonals must contain 1–9. Free, with a worked example.
• Hyper Sudoku (Windoku) — play freePlay Hyper Sudoku, also called Windoku: classic rules plus four extra shaded 3×3 regions that must each contain 1–9.
• Killer Sudoku — play freeLearn Killer Sudoku: classic rules combined with cages that sum to a target and never repeat a digit. The "rule of 45" explained.
• Jigsaw Sudoku (Irregular) — play freeLearn Jigsaw Sudoku, also called Irregular Sudoku: the 3×3 boxes are replaced by irregular jigsaw-shaped regions that each contain 1–9.
• Kropki Sudoku — play freePlay Kropki Sudoku: classic rules plus white dots (consecutive) and black dots (2:1 ratio) between neighbouring cells. Free, with difficulty levels.
• Thermo Sudoku — play freePlay Thermometer Sudoku: classic rules plus thermometers whose digits must increase from the bulb to the tip. Free, with difficulty levels.
• Arrow Sudoku — play freePlay Arrow Sudoku: classic rules plus arrows whose circled digit equals the sum of the digits along the arrow. Free, with difficulty levels.
• Samurai Sudoku — guideLearn Samurai Sudoku: five overlapping 9×9 grids that share corner boxes, played as one giant interlocked puzzle.