Peter Ritmeester is the inventor of the Hyper Sudoku, where four gray regions also contain 1-9. Almost all puzzlers familiar with the Hyper prefer it to standard sudoku: the four gray regions provide for some nice extra logic and the information you are looking for is hidden in four more regions. This is part 1 of the series ●●●● For more than a decade Ritmeester has published these Hypers in The International New York Times and many other newspapers worldwide. Books of his sudoku puzzles — 200+ presented by Will Shortz — have been on the bestseller lists in the US for more than ten years.