Sudoku Variants
fifteen twists on sudoku · 4×4 to 9×9

Play Sudoku Variants — X, Jigsaw, Kropki, Thermo and more

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Tap a square, then a digitN notes · Shift+digit quick noteArrows move

How to play Sudoku Variants

Sudoku variants keep the classic rule — every row, column and box holds each digit once — and add a twist that changes how you think.

Sudoku X adds the two diagonals. Windoku adds four extra windows. Jigsaw swaps the boxes for irregular pieces. Kropki uses white dots (one apart) and black dots (double). XV marks pairs that add to 10 or 5. Anti-Knight and Anti-King forbid repeats a chess move apart. Non-Consecutive keeps neighbours from being one apart. Even–Odd shades squares by parity. Thermo makes digits rise along thermometers. Sandwich totals the digits between 1 and 9 in each line, Arrow circles equal the sum along their arrow, Little Killer totals run down diagonals, purple Consecutive Lines hold runs of consecutive digits, and green Whisper Lines keep neighbours at least 5 apart.

In Kropki and XV every possible clue is shown, so the absence of a dot or letter is a clue too — many Kropki puzzles here start with no digits at all.

How to play Sudoku Variants

Classic sudoku — every row, column and box holds each digit once — plus one extra rule that depends on the variant.

The rules

  1. All variants: each row, column and box (or jigsaw piece) contains every digit exactly once.
  2. Sudoku X: both main diagonals also contain every digit once. Windoku: the four shaded 3×3 windows do too.
  3. Jigsaw: the boxes are replaced by irregular pieces of the same size.
  4. Kropki: a white dot joins digits one apart; a black dot joins digits where one is double the other; no dot means neither. XV: X joins digits adding to 10, V adding to 5; no letter means neither.
  5. Anti-Knight / Anti-King: squares a knight’s move apart / touching squares never repeat a digit. Non-Consecutive: side-by-side squares never hold consecutive digits.
  6. Even–Odd: grey squares are even, grey circles odd. Thermo: digits strictly increase from each thermometer’s bulb to its tip.
  7. Sandwich: a number outside a row or column is the total of the digits between the 1 and the 9. Arrow: a circled digit equals the sum of the digits along its arrow. Little Killer: a number outside points down a diagonal and gives its total.
  8. Consecutive Lines (purple): the digits on a line form a consecutive run in any order. Whisper Lines (green): neighbouring digits along the line differ by at least 5 (3 in a 6×6).

Playing here

  1. Pick a variant, a size and a difficulty, then press New Puzzle. The extra rule is shown under the grid.
  2. Tap a square, then a digit on the number pad (or type it). Or tap a digit first and then the squares you want it in.
  3. Switch to Notes (N) to pencil in candidates; hold Shift while typing for a quick note.
  4. Clashes turn red as you go. Hint explains the next digit, including any variant reasoning that leads to it.

Tips

The full guide, with a worked example and common mistakes: How to play Sudoku Variants.

Questions

Which variant should I start with?

Even–Odd or Sudoku X — they feel most like classic sudoku. Then try Jigsaw and Kropki.

Why are there no digits in some Kropki puzzles?

Because every dot is shown, the dots and gaps alone are enough to lead to one answer.

Is there always one answer?

Yes — every puzzle here is checked to have exactly one solution.

Can I enter a variant puzzle from a book?

Yes — open the Sudoku Variants Solver, choose the variant and enter the givens and clues.

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