More challenges for the sudoku warrior! These 77 puzzles begin with typical sudoku-solving techniques, but then grow more complicated. Instead of figuring out just one game, you have to complete five multiple grids with overlapping corners. No grid is solvable on its own, and sometimes, you'll even have to work on two games at once in order to emerge victorious. An introduction, with a sample puzzle, lays out the strategies. It's loads of fun for the dedicated fan.