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Lizely

Pipes Puzzle

Rotate nine fixed pipe tiles until every opening matches a neighbor and all tiles form one connected network without a closed loop.

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How to use

  1. 1.Select a pipe tile with the arrow keys and press Space or Enter to rotate it clockwise by 90 degrees.
  2. 2.Match every opening with the opposite opening on a neighbor; never point a pipe outside the board or leave separate groups.
  3. 3.Connect all nine tiles as one loop-free network, then use Restart to restore the scramble or Escape twice for the boss screen.

About Pipes Puzzle

Pipes Puzzle is a compact version of the connection game also known as Net, FreeNet, or NetWalk. Nine tiles occupy a three by three grid, and every tile contains one or two pipe openings. Tiles stay in their positions but can rotate in 90-degree steps. The goal is to orient all nine so every opening meets a reciprocal opening on the neighboring tile, no opening points outside the board, every tile belongs to one connected network, and that network contains no closed loop.

The rule contract follows Simon Tatham's maintained Net documentation and an independent Puzzolve guide. Tatham describes a shuffled network restored by rotating tiles until it is entirely connected with no closed loops. Puzzolve independently specifies reciprocal openings, one unified network, no boundary-facing openings, rotation without movement, and an acyclic tree structure. The exact 3 by 3 snake fixture, initial rotations, symbols, controls, and score are Lizely product choices rather than universal Pipes settings.

Move the selected tile with the arrow keys. Press Space or Enter to rotate it clockwise by 90 degrees. Mouse and touch users can click a tile to rotate that tile directly. The cursor stops at board edges and never wraps. Pipe shapes are rendered with text line glyphs representing one of four opening bits: up, right, down, and left. A rotation shifts every opening clockwise while preserving the tile's position and number of openings.

The disclosed solved network follows a snake through every cell: across the top row, down the right side, back across the middle, down the left, and across the bottom. It contains nine vertices and eight reciprocal edges, the exact edge count of a connected acyclic tree. The initial board rotates its tiles by a repeating one, two, three-turn scramble. Reversing those orientations takes 18 clockwise rotations and earns 820 points from a starting value of 1,000.

Validation runs after every rotation. For every opening, the browser calculates the neighboring row and column. An opening outside the grid is a loose edge. An opening facing a neighbor without the opposite bit is a mismatch. Reciprocal links build an undirected adjacency graph, which is traversed from the first tile to count connected cells. A disjoint-set cycle check rejects any link that joins vertices already in the same component. Completion requires zero mismatches, all nine tiles reached, exactly eight edges, and no cycle.

The status line reports the current loose-end count and number of cells connected to the first tile. An unsolved board is explicitly detected as a deadlocked orientation, but it remains editable because rotating a tile can repair it. Completion freezes rotations to keep the final result stable until Restart. Automated tests cover tile rotation without movement, reciprocal edges, outward openings, all-nine connectivity, the eight-edge invariant, cycle prohibition, up-to-right rotation, fixed table sizes, the initial deadlock, and the full 18-rotation completion sequence.

Each tile exposes its index and current opening mask to assistive technology, and the selection has a visible outline. The board uses Lizely CSS variables for its surface, lines, foreground, accent, and focus states. There is no canvas, animation loop, sound, downloaded art, random generator, or server call. A completed best score may be stored only in localStorage. Restart restores all nine scramble rotations, cursor, score, moves, and live analysis.

Press Escape twice within 400 milliseconds to cover the puzzle with the shared simulated operations spreadsheet, then repeat the double press to return to the unchanged network. Use Pipes as a short spatial-network challenge, not as a measure of ability or attention. For more connection puzzles, try Numberlink, Hashi Bridges, Hitori, or Tents.

Methodology & sources

Each pipe mask uses bits 1,2,4,8 for up,right,down,left. Clockwise rotation shifts the four-bit mask. Validation requires every opening to have an in-bounds reciprocal neighbor, builds an undirected adjacency graph, breadth-first counts connected tiles, and uses disjoint-set union to detect cycles. A 9-tile solution must have zero mismatches, 9 connected vertices, 8 edges, and no cycle. Score is max(0, 1000 − 10×rotations).

Frequently asked questions

Can I move or swap pipe tiles?
No. Standard Net-style play keeps every tile in its cell and only changes its orientation.
What counts as a loose end?
An opening is loose when it points outside the grid or faces a neighbor that does not open back toward it.
Why are loops forbidden?
The target is one connected acyclic network. With nine connected tiles, that means exactly eight reciprocal edges.
Is this board random?
No. It uses a fixed 3 by 3 snake network and disclosed rotation scramble so completion is reproducible.

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