Slitherlink: Loop Logic Puzzle

Slitherlink is a classic Japanese logic puzzle loved around the world under many names - Loop the Loop, Fences, Loopy. It starts with a grid of dots and a handful of numbers. Your goal: connect those dots with lines to form one single continuous loop. Each number tells you how many of its four sides the loop touches. Blank cells can have any number of sides. The loop never crosses itself, never branches, never leaves a dead end - just one clean, unbroken loop that fits every clue exactly.

The rules fit in your head after one minute - what unfolds from there is harder to explain.

You start with what you know for certain. A corner cell with a 3 almost draws itself. Two adjacent clues pull at each other in ways you begin to feel before you can name. Gradually a logic vocabulary builds inside you - not memorised, but discovered, puzzle by puzzle. Each new grid teaches you something about what a loop can and cannot do. That slow accumulation of insight is what makes Slitherlink one of the most beloved deductive puzzles ever invented in Japan, and what keeps solvers coming back years after they first pick it up.

This app is designed to give you the full Slitherlink experience, start to finish.

399 hand-crafted loop puzzles, and the first time you sit down with one, you might wonder if it is too easy. It is not. The early puzzles are small and forgiving - a good place to find your footing and start building the instincts that carry you forward. By the time you reach the larger grids, something has shifted. You are reasoning differently. Patterns that once stumped you become starting points. The big puzzles that looked impossible on day one start to look like puzzles you can actually solve - because by then, you can.

A guided start walks you through the logic from the very beginning. You do not need to know anything about Slitherlink to pick this up - just the enjoyment of figuring things out. When you get stuck, Hint, Auto-X, and Check are there to nudge you in the right direction without taking over. The satisfaction of closing the loop yourself is the whole point, and these tools are designed to protect that.

Drawing the loop feels good too. Drag to trace your line across the board, tap to mark a dead edge, and undo any time. The board is clean and focused. Every puzzle has one unique solution, verified. When the loop finally closes and every clue is satisfied, something clicks - and that click is the reason people have been solving Slitherlink puzzles for decades.

Slitherlink is a brain training puzzle in the truest sense - not a reflex test, not a race against the clock, but a logic workout that rewards patience, pattern recognition, and careful reasoning. A brain game for your morning coffee, your lunch break, or a quiet moment before bed. A number puzzle you can put down at any time and pick up exactly where you left it.

The loop is waiting.

Surround the numbers. Close the loop. Train your brain.