Slitherlink

Objective

Draw a single simple loop along the dotted grid. The loop is the fence. It must not branch, cross, or leave a dangling end.

Numbers

A number inside a cell tells you how many of that cell’s four edges belong to the loop. Empty cells have no count — the loop may or may not pass them.

• 0 — none of the four sides is on the loop.
• 1, 2, 3 — exactly that many sides are on the loop. A 4 never appears: that would close a tiny box, not a single outer fence.

Corners

At every dot the loop either passes through (exactly two lines) or stays away (none). Three lines at a dot is a branch; one line is a dead end.

Controls

• Tap or click an edge: empty → line → × (not a line) → empty.
• Right-click, or press X, to mark an edge as not on the loop.
• Check highlights numbers and dots that already contradict the rules.
• Hint draws one correct remaining edge. Arrow keys move the focus; Space cycles the edge; H hints; U undoes; C checks.

Difficulty

• Easy: 5×5 with more numbers.
• Classic: 6×6
• Hard: 7×7 with fewer clues.

Daily challenge

Everyone receives the same uniquely solvable puzzle. It resets at midnight UK. The first solve of the day counts for the league and your streak.