12
23
13
156
XY-Chain
A chain of bivalue cells linked on shared digits, beginning and ending on the same digit Z. One of the two end cells must be Z — so any cell seeing both ends loses Z.
There's a move in the grid.
A chain of bivalue cells linked on shared digits, beginning and ending on the same digit Z. One of the two end cells must be Z — so any cell seeing both ends loses Z.
There's a move in the grid.