Slitherlink Strategy: Zeros First, and the Loop Obeys Rules

0️⃣Step zero: bury the zeros

Every 0 forbids all four of its edges. Cross them all out before you think about anything else — on a typical DailyGrid board this one pass eliminates dozens of edges and quietly solves the neighbourhood of every 0: any numbered cell touching a 0 has that shared edge crossed out, so a 2 next to a 0 only needs one more of its remaining three edges, a 1 next to a 0 needs its one edge among three, and corners of the loop start announcing themselves.

🧪Worked example — a real DailyGrid board

From the Wednesday, October 14, 2026 board (8×8). It is a zero-rich board: crossing out the zeros' edges alone marks 68 crosses — nearly half the grid decided before a single line is drawn. Then the falls start:

The trapped 2. Look at the 2 in row 7, column 2. The cell above it is a 0, and the cell to its right is a 0 — so its top edge and its right edge are already crossed out by step zero. A 2 with two edges gone has no freedom left: its left and bottom edges are both loop. Draw them. That in turn feeds the vertex rule (below) at its two new corners, and the bottom-left of the board starts to unzip — the corner 1 at the very bottom-right of this board eventually keeps exactly one edge, its top, for the same family of reasons.

Notice what didn't happen: no guessing, no trial and error. Zeros, then cells the zeros cornered, then vertices the new lines cornered. Most Slitherlink boards are this polite if you take the free information in order.

📐The corner rules

• 3 in a corner: both board-edge sides are loop, and the two edges that continue from the cell's inner corner (the ones that would extend its other two sides) are crosses. The strongest opening mark in the game.
• 1 in a corner: the two board-edge sides are crosses — the loop can only touch this cell from inside the board, exactly once.
• 2 in a corner: the two edges extending from its inner corner are loop — the path must pass around the back of the cell.
• Two 3s side by side (anywhere): the three vertical edges around and between them — left of the first, the shared edge, right of the second — are all loop, and the edges continuing outward from the pair's middle corners are crosses. A free six-mark pattern; take it whenever it appears.

•The vertex rule — the loop never branches

At every dot, the final loop has either 0 or 2 line-ends — never 1, never 3. That single fact does constant work:

• A dot with 2 lines drawn: cross out every other edge at that dot.
• A dot with 1 line drawn and two of its other edges crossed out: the last edge must be a line — a path that enters a dot has to leave it.
• A dot with 3 crosses: the fourth is a cross too (a lone line-end is illegal).
• And the endgame guard: any line that would close a small loop while numbered cells remain unconnected is a cross — the answer is one loop, not several.

⚠️Common mistakes

• Drawing lines before crosses. Crosses are information; lines drawn on vibes paint you into corners the vertex rule then has to rescue you from.
• Forgetting the inside/outside read. Late in a solve, shade mentally: the loop separates inside cells from outside ones, and a numbered cell's count is about its border — a nearly-surrounded 1 with two border edges drawn is a contradiction somewhere upstream.
• Closing the loop early. It feels like progress and it ends the puzzle wrongly. If unlooped clues remain, the loop isn't done — the closing edge is a cross.

❓FAQ

What's the first move?

Cross out every edge of every 0. Then work the numbered cells the zeros cornered.

What does a corner 3 mean?

Both board-edge sides are loop; the two continuations from its inner corner are crosses.

Why can't I close a small loop?

One loop only. A closing edge with clues still unconnected is always a cross.

Where are the basic rules?

In the companion guide: How to Play Slitherlink.

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