Slitherlink is a fascinating logic puzzle where you draw a single closed loop on a grid using clues. If you are new to it or want to sharpen your skills, here are 5 essential techniques.
1. The Zero Clue Elimination
When you see a 0 in a cell, immediately mark all four edges around it as "no line." This is the simplest and most powerful move.
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Every edge around the 0 is guaranteed to have no line.
2. Corner 3 Pattern
A 3 in any corner of the grid forces two edges along the grid border. The corner vertex must have exactly 2 lines passing through, and with 3 required edges, two must be the border edges.
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3. Adjacent 3-3 (S/Z Shape)
Two 3s next to each other horizontally or vertically create an S-shaped or Z-shaped line pattern. They share a middle edge, with alternating top/bottom (or left/right) edges.
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4. The Vertex Degree Rule
Every vertex (dot) in the puzzle must have either 0 or exactly 2 lines passing through it. If a vertex already has 2 lines, all other edges at that vertex are definitely "no line." If a vertex has 1 line and only one other possible edge, that edge must also be a line.
5. Short Loop Prevention
The solution must be a single closed loop. If drawing a line would create a small closed loop disconnected from the rest, that line is impossible. Always check: "Would this close off a section prematurely?"
Try It Yourself!
Practice these techniques on Slitherlinks.com — 1,900+ free puzzles across 5 grid sizes and 3 difficulty levels. Start with 5×5 easy puzzles and work your way up!
Happy solving! 🧩
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