Heyablock ("Heyawake-Block") is a logic puzzle invented by Atsumi Hirose (Japan). A rectangular or square grid is divided into regions. The aim is to blacken some cells of a grid according to the following rules:
All black cells in a region must be connected.
A cell with a number indicates how many cells in the region must be blackened.
In regions without a number any amount of cells may be blackened (at least one).
When two cells are orthogonally adjacent across a region boundary, at least one cell must be white.
All white cells form one orthogonally connected area.
A line of connected white cells cannot go through two or more region borders.
Heyablock is a logic puzzle where players blacken cells in a grid divided into regions. Numbers in some regions indicate the number of cells to be blackened, while others can have any number. Black cells must be connected within each region, and white cells must form one connected area without crossing multiple region borders.