Original
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Fill the grid with numbers from 1-9. Each digit must appear exactly once in each row, each column, and each 3x3 grid.
Colodoku
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Cells of the same colour cannot host the same number. Fill the grid with numbers from 1-9. Each digit must appear exactly once in each row, each column, and each 3x3 grid.
Shapedoku
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The sum of cells within a shape must equal the number of sides of that shape. Fill the grid with numbers from 1-9. Each digit must appear exactly once in each row, each column, and each 3x3 grid.