Chocona is a binary determination puzzle in which the cells in a grid are split into either shaded or unshaded.
The objective is to shade some cells, subject to the following rules:
- Numbers indicate how many shaded cells are in a region.
- Shaded cells must form rectangles, independently of the region borders.
- Shaded rectangles must not touch horizontally or vertically.
A standard 10x10 chocona and its solution.