Slitherlink Puzzles
Connect edges into one closed loop, using each number to count how many of its four sides belong to the path.
Hints available. Play as many boards as you like.
Ready when you are.
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How to play
Tap an edge to cycle it between part of the loop, ruled out, and unknown. A number inside a cell tells you exactly how many of its four edges are used.
The finished path must be one continuous closed loop. It cannot branch, cross itself, stop at a loose end or form two separate loops.
Dots may have either zero or two loop edges touching them. That local rule works together with the numbered cells to determine the next segment.
Strategy
Use the 3-in-a-corner rule. When a 3 sits in an outer corner, both boundary edges must belong to the loop; the clue needs three sides and there is no legal way to omit either boundary side.
For adjacent 3 clues, their shared edge is forced and the outside parallel edges are often forced as well. Marking ruled-out edges at the same time prevents accidental branches.
Delay closing a small circuit. If a move completes a loop while untouched clues remain outside it, that edge cannot be correct because the final answer must be a single loop.
Difficulty and variants
Easy boards keep more clues, especially near corners. Hard boards remove local footholds and rely on reachability and single-loop arguments across a larger area.
Questions, answered
Can a Slitherlink loop touch itself?
The loop may pass near itself, but it cannot branch or cross. Every used dot has exactly two connected loop edges.
Can Slitherlink have more than one loop?
No. All numbered clues and edge rules must be satisfied by one continuous closed loop.
What does a zero mean in Slitherlink?
None of that cell’s four edges can be part of the loop, so mark all four as ruled out.