Normal sudoku rules apply. There are three "rings" in the grid, or increasingly larger squares, with some breaks in them, represented by the yellow lines. Along these rings, digits must touch at least one other consecutive digit on the ring, except in the 'breaks' of the ring (where there is no line), where digits must not touch another digit consecutively on its ring. (so r1c4 can never be consecutive with either r1c3 or r1c5). These rules do not apply to cells on different rings that touch each other. Black dots show that the 2 joined cells have a 1:2 ratio, and not all possible black dots are given.