Standard

Place the digits 1–9 in every row, column and box.

Fog of war

The grid is initially partially covered in fog. Entering digits clears the fog surrounding the entered digit.

The puzzle has a unique solution.

Standard

Place the digits 1–9 in every row, column and box.

Little killer

The digits along a diagonal marked with a number sum to that number. Digits on such a diagonal can repeat if allowed by other rules.

Choco banana

Shade some cells to form some shaded and unshaded orthogonally connected regions. Shaded regions must be rectangular. Unshaded regions must not be rectangular. Circled digits give the size of the enclosing region. Uncircled digits do not.

Killer

Digits within a cage may not repeat, and sum to the number in the upper-left corner if given.

Arrow

Digits along an arrow sum to the digit in the bulb. Digits on an arrow can repeat if allowed by other rules.

Hypercube

The grid represents a 3×3×3×3 hypercube. Place the digits 1–9 in each 3×3 orthogonal square within it. These are: the rows, columns and boxes; the cells in the same position in each box (eg r147c147); the left, middle and right vertical slices of a row of boxes (eg r123c147); and the top, middle and bottom horizontal slices of a column of boxes (eg r147c123).

Thermo

Digits increase along a thermometer away from the bulb.

Hypercube

The grid represents a 3×3×3×3 hypercube. Place the digits 1–9 in each 3×3 orthogonal square within it. These are: the rows, columns and boxes; the cells in the same position in each box (eg r147c147); the left, middle and right vertical slices of a row of boxes (eg r123c147); and the top, middle and bottom horizontal slices of a column of boxes (eg r147c123).

Arrow

Digits along an arrow sum to the digit in the bulb. Digits on an arrow can repeat if allowed by other rules.

Hypercube

The grid represents a 3×3×3×3 hypercube. Place the digits 1–9 in each 3×3 orthogonal square within it. These are: the rows, columns and boxes; the cells in the same position in each box (eg r147c147); the left, middle and right vertical slices of a row of boxes (eg r123c147); and the top, middle and bottom horizontal slices of a column of boxes (eg r147c123).

Killer

Digits within a cage may not repeat, and sum to the number in the upper-left corner if given.

Standard

Place the digits 1–9 in every row, column and box.

Disjoint

Place the digits 1–9 in every box position. For example, every digit appears in the upper-left corner of some box.

Anti-knight

Cells a chess knight’s move apart may not contain the same digit.

Kropki

Digits separated by a white dot have a difference of 1. Digits separated by a black dot have a ratio of 2. Unless otherwise specified, all such dots are given.

No negative Kropki constraint: not all dots are necessarily given.

Standard

Place the digits 1–9 in every row, column and box.

Disjoint

Place the digits 1–9 in every box position. For example, every digit appears in the upper-left corner of some box.

Anti-knight

Cells a chess knight’s move apart may not contain the same digit.

Standard

Place the digits 1–9 in every row, column and box.

Arrow

Digits along an arrow sum to the digit in the bulb. Digits on an arrow can repeat if allowed by other rules.

Clones

The marked areas are clones of each other, and contain the same digits in the same positions.

Standard

Place the digits 1–9 in every row, column and box.

Arrow

Digits along an arrow sum to the digit in the bulb. Digits on an arrow can repeat if allowed by other rules.

Killer

Digits within a cage may not repeat, and sum to the number in the upper-left corner if given.

Little killer

The digits along a diagonal marked with a number sum to that number. Digits on such a diagonal can repeat if allowed by other rules.

Diagonal

The marked long diagonal does not contain repeated digits.