Normal sudoku rules apply. In addition, both marked diagonals contain the digits 1-9 exactly once. If two consecutive digits are adjacent in the completed grid, the edge between them is marked with a white dot. Similarly, if two digits along the two main diagonals are consecutive, they have been separated by a grey dot. All possible white and grey dots are provided. If two cells contain the same digit, the "taxicab distance" cannot be equal to that digit. The "taxicab distance" is the minimum number of orthogonal moves from cell A to cell B. For example, if there is a 4 in R3C4, there cannot be a 4 in R2C7, since it takes a minimum of 4 moves to go from R3C4 to R2C7.