Sudoku and Slitherlink are both grid-based logic puzzles you solve by pure deduction, so solvers naturally wonder how alike they really are. The short answer: Slitherlink is distant to Sudoku. Below we lay out what the two share, where they part ways, and whether the skills you have built on Sudoku will carry over.
- Grid: Dots-and-edges grid
- Closeness to Sudoku: Distant
- Also called: Loop the Loop, Fences
What is Slitherlink?
Draw a single continuous loop along the grid lines so that each numbered cell has exactly that many of its four edges used. Here are the rules in full:
- Connect dots with horizontal and vertical segments to form one closed loop.
- A number in a cell says how many of its four edges the loop uses.
- The loop never crosses itself or branches.
What a Slitherlink looks like
A Slitherlink is a grid of numbered cells, and you draw a single closed loop on the grid lines so each number has that many of its four edges used. Here is a small solved one — the purple loop runs around all four "2" cells, giving each exactly two edges.
A solved Slitherlink: the loop gives each "2" cell exactly two of its edges.
Both are pure-logic, single-solution puzzles, and both reward marking impossibilities — here edges that cannot be part of the loop. But you draw a loop on the edges, not digits in the cells, and there is no row, column or region rule. The most distant relative.
What Slitherlink shares with Sudoku
- Both are pure-logic puzzles with a single solution reached without guessing.
- Both reward marking impossibilities — here, edges that cannot be part of the loop.
How Slitherlink differs from Sudoku
- You draw a loop on the edges, not digits in the cells.
- The numbers are edge counts, and there is no row, column or region rule.
Do Sudoku skills transfer?
Nothing places digits here, so no Sudoku technique applies directly — but the discipline of proving each mark before committing is the very habit Sudoku trains.
The verdict
Slitherlink shares Sudoku's logical purity but almost none of its machinery — it's a loop-drawing puzzle, not a filling one.