Sudoku Builder/en
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Instructions
Combine adjacent pairs of 3-square regions to make six contiguous regions of six squares, thus creating a 6x6 Irregular Sudoku: Place a digit from 1 to 6 into each of empty squares so that each digit appears exactly once in each of the following: The six rows, the six columns, and the six newly created regions.
History
Invented by Riad Khanmagomedov (Russia).