Chocona

Chocona ("Chocolate") consists of a rectangular or square grid divided into regions. The aim is to blacken some cells of a grid according to the following rules:

• A cell with a number indicates how many cells in the region must be blackened.
• In a region without a number any number of cells may be blackened.
• The black cells must form rectangles, independently of the region borders.
• The black rectangles must not be orthogonally adjacent.

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