Rainbow Sudoku: 1-9 in each row, column, and block, and in each collection of same-colored cells; for example, the nine yellow cells contain 1-9.Product Sudoku: 1-9 in each row, column, and block, where the number in each shaded region is equal to the product of its entries. 18-Clue Sudoku: 1-9 in each row, column, and block. 18 is the fewest number of clues conjectured to be possible in a rotationally-symmetric puzzle. Lightning Sudoku: 1-9 in each row, column, block, and lightning bolt.Grey Sudoku: 0-9 in each row, column, 2x5 block, and grey shaded region.Tile Sudoku: 1-5 in each pentomino region and 1-5 each twice in each row and column.

8 3 1 74 9

6 17 5

3 2 8 9 59 7 1 0 4

0 36 4

4 33 5 7 9

7 4 5 8 9 2 1

3 5 78 9

1 28 4 2

9 8 1 2 4 3 6

5 71 4 9

9 8 2 46 3 8

5 8 68 6 5 99 6 2

7 8

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