How to play Pipes
Pipes looks like fidgeting, but it's pure deduction: the walls, corners and lamps pin the network down one piece at a time. Here are the rules and the techniques.
The rules
- Every cell holds a pipe piece: a lamp (one end), a straight or elbow (two ends), a T-junction (three), or a cross (four).
- Tap to rotate a piece 90° clockwise; right-click or long-press rotates the other way.
- Two pieces are connected when their ends point at each other.
- The board is solved when every piece is lit from the central source and no end is left open — pointing at a wall or at the side of another pipe.
Solving strategies
- Edges first. No end may point off the board. A straight piece on the border must run parallel to it; a T-junction on the border must face inward; an elbow in a corner has exactly one legal orientation.
- Lamps lock their neighbors. A lamp connects one way only. Once you know which neighbor feeds it, that neighbor must offer an end in return — and its other ends are then constrained too.
- Count ends between neighbors. If a piece has all its ends accounted for, every adjacent piece must turn its ends away from it — that's how deductions travel across the board.
- No loops. The solved network is a tree. If two lit branches would join into a ring, one of those pieces is misrotated.
- Watch the flow. The amber glow is a progress meter: a grey island means its link to the source is still wrong somewhere along the boundary.
A worked example
Take a corner cell holding an elbow: only one rotation keeps both its ends on the board, so it's forced immediately. Suppose its end points at a border straight — the straight must run along the wall, and now its far end pushes into a T-junction on the same wall. A border T-junction must face inward, and with one of its three ends already fed by the straight, only one rotation remains. Three pieces placed without touching the middle of the board — that cascade is the whole game.
Common mistakes
- Spinning instead of reasoning. Random taps light some pieces by luck but stall on the interior. Anchor edges and lamps first — the middle solves itself.
- Leaving micro-leaks. "Everything is lit" isn't enough — a single end pointing at a wall keeps the board unsolved. The lit counter tells you coverage; scan for open ends when it reads full.
- Building rings. If a rotation connects two already-lit pipes, you've made a loop — the real solution never has one.
Frequently asked questions
- What kind of puzzle is Pipes?
- A rotation-logic puzzle from the classic "Net" family: connect all cells into a single leak-free network — a spanning tree of the grid.
- Do I ever need to guess?
- No — every board is generated with exactly one solution and is deducible from the borders, lamps and junction constraints.
- Is there a daily puzzle?
- Yes — a shared 7×7 Daily Challenge with streaks, plus unlimited boards in 5×5, 7×7 and 9×9. Free, no login.