Normal Sudoku rules apply. Cells separated by a knight's move (in chess) cannot contain the same digit. Grey circles and squares must contain odd and even digits respectively. Digits along a solid grey line must form a palindrome. Digits along arrows must sum to the total in their white circle. All of the digits 1 to 9 must appear on both main diagonals. The number outside the grid indicates the sum of the digits along its diagonal. Digits may repeat along the diagonal.