Wamuzu

Wamuzu (Worms) is a Japanese logic puzzle where the objective is to connect all pairs of circles in a grid with a continuous line.

Rules: There must be a line connecting each of the two circles. The individual segments of a line run horizontally or vertically between the centres of orthogonally adjacent cells.
Every cell must have exactly one line crossing it. The length of each line segment must be 1, meaning that every line must turn 90 degrees in every cell.