Author: Andrey Bogdanov
Shade some cells black and then draw a single non-intersecting loop through all white cells. Black cells cannot share an edge with each other. Numbers indicate the number of cells shaded black in the corresponding area.
Grid control: To draw a line press the mouse button at a start cell and move mouse to another cell holding the button. Mouse click at a cell paint the cell black. More details about grid control are at the help page.