How to Play Slitherlink
If you don't know the basic principles of Slitherlink puzzles, please first read the "What is Slitherlink?" section of the FAQs.
To solve a Slitherlink puzzle you must repeatedly place lines on the grid anywhere you can where they logically must be placed. To help you to deduce where lines must be placed, you can also mark with a cross the positions where lines cannot possibly be placed. You cannot use guesswork, you must use logic based on the numbered cells and lines/crosses that you have already placed. As you add more and more lines, they will slowly start to join up until they eventually all join together to form one single loop.
We're going to take this extremely simple 3x3 puzzle and discuss the logical approach to solve it. Everything you learn throughout this example can be applied to larger puzzles.
To begin solving a Slitherlink puzzle, there are some common starting techniques, which are discussed in more detail in the next section of the FAQs. Here we know that no lines can be placed around a 0-numbered cell, so we surround it with crosses.
We now know that there are only three possible lines that can surround the adjacent 3-numbered cell, so we can mark them in.
In Slitherlink puzzles we aim to create a single loop with no intersections, so we therefore know that each dot can have exactly zero or two lines coming from it. Using this logic, we can add more lines and crosses from the dots surrounding the 3-numbered cell.
The loop we have begun to form could either go upwards or downwards at each end. We can see though that going upwards would result in dead-ends. Therefore the loop must continue downwards at both ends.
At this point we don't know which of the 2 sides should be selected around the 2-numbered cell, so we will look at the 1-numbered cell. If you consider selecting each of the 3 remaining sides in turn, and try to complete the rest of the puzzle, you can only reach a successful solution if the bottom side is selected. As it is the only side that can produce a correct solution it must be selected.
At this point the remaining lines that need to be selected are obvious, so we can mark them in and complete our solution.
Now you know how to approach and play Slitherlink puzzles. The example we followed highlighted a number of techniques to work out where we could or could not place lines. For a comprehensive list of techniques and rules to greatly help your Slitherlink puzzle solving efforts, next take a look at the Slitherlink Solving Techniques section.