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.
Cross+A can solve puzzles from 3 x 3 to 30 x 30.