Anti-king sudoku rules
no two squares that touch either horizontally, vertically or diagonally can have the same digit. (As in, no two squares a chess king can move between in a single move.)
Anti King Sudoku is a variant of Sudoku that adds an additional rule: no digit can appear twice on the same diagonal. This means that each of the two main diagonals (the one that runs from the top left corner to the bottom right corner, and the one that runs from the top right corner to the bottom left corner) must contain all nine digits, but no digit can appear more than once in either diagonal.
The rules of Anti King Sudoku are the same as the rules of regular Sudoku, with the addition of the anti-king rule. This means that you must still make sure that each row, column, and 3x3 block contains all nine digits, without repetitions. However, you must also make sure that no digit appears twice on either of the main diagonals.
Anti King Sudoku puzzles can be a bit more challenging than regular Sudoku puzzles, because there are fewer places where you can put certain digits.