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 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. There are 6 boxes with a plus or minus sign where the sum or difference of the number formed by the first two rows is equal to the number formed in the third row of the same box.

Fill in the grid so that every row, every column, and every 3 x 3 box contains the digits 1 through 9. There are 6 boxes with a plus or minus sign where the sum or difference of the number formed by the first two rows is equal to the number formed in the third row of the same box.

Fill in the grid so that every row, every column, and every 3 x 3 box contains the digits 1 through 9. There are 6 boxes with a plus or minus sign where the sum or difference of the number formed by the first two rows is equal to the number formed in the third row of the same box.