Author: Andrey Bogdanov
Draw a single continuous loop in the grid using horizontal and vertical line segments so that the loop visits every cell with clues. It should not cross or overlap itself. The loop may either go straight through or turn at each clues. If the loop goes straight through a clues, the number indicates the length of the straight segment. If the loop turns at a clues, the number indicates the length of both loop segments extending from that circle.
Grid control: To draw a line press the mouse button at a start cell and move mouse to another cell holding the button. More details about grid control are at the help page.