Nurikabe — Quick rules

Goal of the game

Separate numbered white islands with a connected black sea. Every cell must end up as island or sea.

Every white island is connected through sides, contains exactly one clue and has exactly as many cells as its clue, including the clue cell.
Numbered cells stay white. Distinct islands cannot share a side, though corner contact is allowed. No unnumbered white island may remain.
All black sea cells form one side-connected area. The sea may touch the edge; it need not form a loop.
No 2×2 square may be entirely black. Unlike Hitori, neighbouring black sea cells are allowed and often necessary.