Yajikabe

Yajikabe was invented by Naoki Inaba (Japan): he combined Yajilin and Nurikabe puzzles. The goal is to blacken some cells of a grid according to the following rules:

• Cells with numbers are always white.
• No 2 x 2 cell area within the grid can contain all black cells.
• All the black cells form one contiguous region.
• A cell containing a number and an arrow represents how many black cells are in the row or column pointed at by the arrow.

Cross+A can solve puzzles from 4 x 4 to 30 x 30.