Normal sudoku rules apply. The grid contains two “galaxies”. A galaxy is a collection of orthogonally-connected cells which exhibit 180 degree rotational symmetry around the central cell of the grid. Eg If r2c4 is in a galaxy then r8c6 must also be in that galaxy. All cells must be part of a galaxy and the two galaxies may only ever overlap in one cell - the central cell of the grid. No 2x2 area may be fully part of one galaxy. One of the galaxies is “redshifted” and cells in it have a value of one greater than their digit. The other galaxy is “blueshifted” and cells in it have a value of one less than their digit. Values along an arrow sum to the value in that arrow’s circle. Values in a cage sum to the given total. Digits may not repeat in a cage, but values may.