Fill in the grids so that every row, every column and 3x3 box contains the digits 1 through 9. There must be a one-to-one correspondence between both twins, i. e., in all positions with a certain digit in the first grid must be in the corresponding position in the second grid also always the same digit (possibly another as in the first grid). Numbers going along grey lines must be in increasing or decreasing order from one end to the other.

Fill the grid with the digits 1 to 9. The digits represent the height of the skyscraper in each cell. Each row, column and 3x3-box has exactly one of each digit. The clues along the edges tell you how many skyscrapers you can see from that vantage point. The red points in the near of crosses where four cells meet each other show that the cell with the red point is greater then the three other ones.

Fill the grid with the digits 1 to 9. The digits represent the height of the skyscraper in each cell. Each row, column and 3x3-box will have exactly one of each digit. The clues along the edges tell you how many skyscrapers you can see from that vantage point. Heights of skyscrapers must be placed according to greater (>) and less (<) signs.

Put the numbers 1 through 9 into the hexagonal cells so that every line (of any length) contains every digit not more than once. The greater less sign show in which cell the greater value is.

Smaller example with the numbers 1 through 6:

Puzzle:

Fill in the grid so that every row, every column, and every 3x3 box contains the digits 1 through 9. The colored extra-regions must contain each the digits 1 through 9.

In each 3x3 box their is a differet rule to follow:

- Upper left - Consecutive Sudoku: All neighbouring cells with consecutive digits have a colored border.
- Upper centre - Killer <=>: Relation signs represent the relation between the sums of the digits in the sub-regions.
- Upper right - Greater/Less Sudoku: The inequality between each pair of digits must stand correct.
- Centre left - Arrow Sudoku: The digit in a circle is the sum of the digits which are marked with its arrow.
- Centre - Magical square: the sum of any row, any column and both main diagonals in this area is always the same.
- Centre right - Product Sudoku: Digits in a sub-region multiply up to the specified number.
- Lower left - Addoku: Digits in the outside equal the sum of the three numbers of the corresponding row or column in the contigous box.
- Lower centre - Killer: Digits in a sub-region add up to the specified number.
- Lower right - Sum Box Sudoku: First two row of numbers add up to the number formed on the third row.

This combination variant was introduced by Cihan Altay at the 1st Sudoku World Championship.

Fill in the grid so that every row, every column, and every 3x3 box contains the digits 1 through 9. The colored extra-regions must contain each the digits 1 through 9.

In each 3x3 box their is a differet rule to follow:

- Upper left - Digital Sudoku: Digits are in digital form, as given below.
- Upper centre - Even/Odd Sudoku: Yellow cells must contain odd digits, green cells must contain even digits.
- Upper right - Consecutive Sudoku: All neighbouring cells with consecutive digits have a colored border.
- Centre left - Sum Sudoku (Killer Sudoku): Digits in a sub-region add up to the specified number.
- Centre - Classical Sudoku: No special rule.
- Centre right - Pips Sudoku: Digits are given as pips, like on dominoes or dices, as given below.
- Lower left - Big/Small Sudoku: Red cells must contain small digits (1 - 4), blue cells must contain big digits (5 - 9).
- Lower centre - Greater/Less Sudoku: The inewquality between each pair of digits must stand correct.
- Lower right - Sum Box Sudoku: First two row of numbers add up to the number formed on the third row.

Fill in the grid so that every row, every column, every 3x3 box and both diagonals contain the digits 1 through 9. A red arrow means that the digits are going up till they hit this number and for a cyan arrow they go down till they hit this particular number.

For example:

135247896 could get a red arrow with a 5 or a cyan arrow with a 1.

932415678 could get a red arrow with a 9 or a cyan arrow with a 2.

Fill in the grid so that every row, every column, and every 3 x 3 box contains the digits 1

through 9.

A red arrow means that the digits are going up till they hit this number and for a cyan arrow

they go down till they hit this particular number.

For example:

135247896 could get a red arrow with a 5 or a cyan arrow with a 1.

932415678 could get a red arrow with a 9 or a cyan arrow with a 2.

The sums of the digits within each sub-region are equal to each other. In sub-regions there can't be the same digit repeated.

Fill the grid with the digits 1 to 9. The digits represent the height of the skyscraper in each cell. Each row, column and 3x3-box will have exactly one of each digit. The clues along the edges tell you how many skyscrapers you can see from that vantage point.

In each 3x3 box their is a different rule to follow:

- Upper left - Even/Odd Sudoku: Yellow cells must contain odd digits, green cells must contain even digits.
- Upper centre - Min Max Quad Sudoku: The red points in the near of crosses where four cells meet each other show that the cell with the red points is greater then the three other ones. The blue rings in the near of crosses where four cells meet each other show that the cell with the blue ring is smaller then the three other ones.
- Upper right - Arrow Sudoku: The digit in the circle is the sum of the digits which are marked with its arrow.
- Centre left - Difference Sudoku: The numbers between two cells give the difference of the digits.
- Centre - Navigator Sudoku: The arrows show the location of the same number in the previous or next column or row. So for example, the arrow in fifth column means that the same digit is in the sixth column in row 6 - 9.
- Centre right - Greater/Less Sudoku: The inequality between each pair of digits must stand correct.

Fill in the grid so that every row, every column, and every 3x3 box contains the digits 1 through 9. In each green line the numbers are alternating larger and smaller.

Smaller example:

Puzzle: