These sudoku are easy to read, but challenging to solve - because every one of the 225 puzzles breaks out of the usual 9x9 mould. Variants include Irregular Sudoku, which replaces the usual 3x3 boxes with jigsaw-like shapes and Diagonal Sudoku, in which the long diagonals also contain the digits 1 through 9 exactly once each. leírás elrejtése