Normal sudoku rules apply. Colour each cell in the grid either red or blue, such that no 2×2 square is a single colour and the cells of each colour form a single orthogonally connected region. Every line that passes through at least one red cell is an alternating-parity line (i.e. each pair of consecutive digits along the line must include one even and one odd digit). Every line that passes through at least one blue cell is a region-sum line (i.e. box borders divide the line into segments with equal sums; these sums may vary between lines). Any line that passes through both red and blue cells is also a renban (i.e. it contains a set of consecutive, non-repeating digits in any order).