All Sudoku Variants

Both main diagonals must also contain 1–9

Four extra shaded 3×3 boxes must each contain 1–9

Five overlapping 9×9 grids sharing corner boxes

Irregular jigsaw-shaped regions replace the standard 3×3 boxes

Combines jigsaw regions with main diagonal constraints

Digits must strictly increase along thermometer shapes

Digits on an arrow must sum to the digit in the circle

Purple lines must contain consecutive digits in any order

Adjacent digits on the green line must differ by at least 5

The digit sequence along a line reads the same forwards and backwards

Digits on a line must fall strictly between the two endpoint values

Clues outside the grid give the sum of a diagonal

Clues give the sum of digits between the 1 and 9 in each row/column

Outside clues show how many 'buildings' are visible from that edge

Digits outside the grid must appear in the first three cells of that row or column

White dots = consecutive digits; black dots = one digit is double the other

X between cells means they sum to 10; V means they sum to 5

Bars between cells mean those two digits are consecutive

No two orthogonally adjacent cells may contain consecutive digits

Inequality signs between cells constrain which is larger

Shaded cells must contain odd digits; circles must contain even digits

No two cells a king's move apart may contain the same digit

No two cells a knight's move apart may contain the same digit

Orthogonally adjacent cells may not contain consecutive digits

4×4 or 6×6 grids — perfect for beginners and children

Sudoku arranged on the faces of a cube or other 3D layout

Uses letters instead of numbers — and often spells a word in one row

Marked regions must contain identical digit arrangements

You must determine the region boundaries as part of solving

A pencilmark-style variant where clues are given as candidate sets