These sudoku are easy to read . . . but challenging to solve, because every one of the 225 puzzles breaks out of the usual 9x9 mold. Try variants such as Irregular Sudoku, which replaces the usual 3x3 boxes with jigsaw-like shapes; Diagonal Sudoku, in which the long diagonals also contain the digits 1 through 9 exactly once each; and more!
