Normal sudoku rules apply. A digit on a bent arrow shows how many cells away the digit in the cell from which the arrow originates appears in the direction of the arrow, e.g. if R1C4 was a 3, then whichever digit is in R2C4 would also be in R1C1. Under the fog, a double-headed arrow is two overlapping slingshots, and adjacent digits along a green line differ by at least 5.