### Diagonal

Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3×3 regions. Additionally, each digit appears exactly once in each of the two main diagonals.

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### Diagonal Even

Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3×3 regions. Additionally, each digit appears exactly once in each of the two main diagonals and the grey squares in the grid must contain even digits.

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### Diagonal Odd

Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3×3 regions. Additionally, each digit appears exactly once in each of the two main diagonals and the grey squares in the grid must contain odd digits.

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### Even

Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3×3 regions. The grey squares must contain even digits.

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### Irregular

Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the irregularly shaped regions.

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### Isosudoku

Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, 9-cell diagonals and the nine outlined 3×3 regions. In the shorter diagonals all digits must be different.

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### Killer

Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3×3 regions. The sum of the numbers in each outlined region is equal to the corresponding number given in a corner of the outline. No digit is repeated within a given outlined region.

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### Kropki

Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3×3 regions. If absolute difference between two digits in neighbouring cells equals 1, then they are separated by a white dot. If the digit is a half of digit in the neighbouring cell, then they are separated by black dot. The dot between 1 and 2 can be either white or black.

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### Little Killer

Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and nine outlined 3×3 regions. Numbers with arrows indicate sum of the numbers in each direction.

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### Lucky Seven

Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3×3 regions. Additionally, each digit appears exactly once in each of the two main diagonals. All neighbouring cells linked with the line contain digits in arithmetical series (e.g. 234) or in a special one (e.g. 76567). Sudoku grid contains highlighted all the squares with even digits.

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### Odd

Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3×3 regions. The grey squares must contain odd digits.

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### Parquet

Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the outlined squares 4×4, all 12 columns, all 12 rows, 9 top left corner, 9 central and 9 bottom right corner highlighted squares.

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