Number: Puzzle #3586 Genre: Sudoku Author: nyancharov Appeared at: April 5, 2013
Is this regular sudoku? The 12-cell inner region should be empty?
The puzzle remains a valid sudoku if the inner region is divided into two 6-cell regions.
The outside border of the 12-cell region is not bordered by a thicker line. This puzzle should follow the same convention (although really you can figure out what is intended anyway).