Around this grid, we’ve embraced revolution, rejecting monarchy. No commonwealth, no unitary authority at all. So no digit repeats within a chess King’s move. Of course, normal Sudoku rules already eliminate repeated digits in orthogonally-adjacent cells, so really an Anti-King constraint only eliminates repeated digits in diagonal neighbors. Wacky kings!
Rules:
Normal Sudoku rules apply.
Diagonally-adjacent cells do not contain the same digit.
Estimated difficulty: 1 out of 5
Solve on SudokuPad