Heyawake

Heyawake is a grid-based puzzle where players shade cells inside rectangular rooms according to strict constraints. Numbered rooms must contain exactly the indicated number of shaded cells, shaded cells cannot be orthogonally adjacent, and continuous lines of unshaded cells cannot span across more than two consecutive rooms.

The name is Japanese and translates directly to 'divided rooms,' which describes the puzzle's grid layout. The grid is explicitly subdivided into various rectangular regions that dictate the puzzle's solving logic.

If a room does not contain a number, it means any number of cells within that room can be shaded, including zero. However, players must still ensure these shaded cells follow the global rules of not touching each other and preventing long unshaded lines.

Like many famous grid logic puzzles such as Sudoku, Heyawake was popularized by the Japanese publisher Nikoli. It frequently appears in their printed puzzle anthologies alongside other spatial constraint games.