Circles and Squares

Circles and Squares is a logic puzzle. A square or rectangular grid contains black and white circles. The aim is to blacken cells of a grid according to the following rules:

• Cells with black circles must be blacken. Cells with white circles cannot be blacken.
• The black cells divide the grid in areas of white cells. These areas must be square.
• No 2 x 2 cell area within the grid can have the black color.
• All the black cells must form an orthogonally continuous area.

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