A grid of square fields is given, some of which contain a line that connects two of the sides (either opposite on a straight path or as a curve two neighboring ones). Some fields can also contain a small circle , a placeholder symbol. The player has the task of making a closed line run through all the fields that are not filled with a circle by drawing in further straight lines and curves. Only one loop may be created, not two separate circles.
As with all such logic puzzles, there is exactly one unique solution.
To solve a loopy puzzle, one typically first tries to determine small fragments of the path sought, which can then be gradually connected to form larger sections. It is avoided to enter parts of the solution whose correctness is still uncertain. At the beginning it is recommended, for example, to draw a curve in all corner fields that are not occupied by a circle, as there cannot be any other part of the route.