Normal sudoku rules apply. Nurikabe: Shade some cells such that all shaded cells are orthogonally connected (water), but no 2x2 area is entirely shaded; groups of orthogonally connected unshaded cells form islands. An island may be of size 1. Every cell with a circle clue is unshaded, and each island contains exactly one circle cell. The digit in this circle cell gives the size of the island. Note that an island may occupy a full 2x2 area (unlike water). Digits may not repeat within an island. Every blue line must contain at least one shaded and at least one unshaded cell. Switching between shaded and unshaded cells divides each line into segments with the same sum. Different lines may have different sums. Digits may repeat on a line if allowed by other rules.