The stones
- Tile
- One square of the board and the piece carved on it. Rune Circuit also calls a tile a stone or a rune. The board has 25 of them.
- Arm
- A carved line running from the center of a tile to one of its four sides. A tile’s arms never change, only the directions they point. Other versions call them wires, cables or pipes.
- Endpoint
- A tile with one arm. It is the tip of a branch. NetWalk-style games draw endpoints as computers or terminals, and they are also called dead ends.
- Straight
- A tile with two arms on opposite sides. It has only two distinct positions: across or up and down. Also called a line.
- Corner
- A tile with two arms on neighboring sides, making a quarter turn. Also called an elbow or a bend. Not to be confused with a corner square of the board.
- Junction
- A tile with three arms and one blank side. Also called a T-piece or a tee.
- Star
- The power source: the one tile every other tile must connect back to. In Rune Circuit it is the star rune in the top-left corner. Other versions call it the server, the source or the power unit.
- Rotation
- A quarter turn of one tile, to the left or to the right. Rotating is the only move in the puzzle.
Connections
- Connection
- Two neighboring tiles whose arms point at each other across the side they share. A connection needs both arms.
- Open side
- A side of a tile that an arm points to. Once you know a side is open, the neighbor across it must have an arm pointing back.
- Closed side
- A side of a tile with no arm. Once you know a side is closed, the neighbor across it must not point an arm at it.
- Matching sides
- The rule that the two tiles on either side of a shared edge must agree: both open or both closed. The tips call working this way “match or block every side”.
- Loose end
- An arm that points at a blank side of its neighbor or at the edge of the board. A solved puzzle has none. Also called a loose arm, an open end or a leak.
- Edge rule
- No arm may point off the board. It fixes many tiles on the border at once, which is why the tips say to start at the edges.
- Powered
- Connected to the star through an unbroken chain of connections. The puzzle is solved when all 25 tiles are powered and no loose end remains.
The network
- Circuit
- The whole connected network you are building, powered from the star. Other versions simply call it the network.
- Loop
- A ring of connected tiles that leads back to where it started. In Rune Circuit a loop always leaves some other tile cut off, so a solved board never contains one.
- Isolated group
- A set of tiles that connect to one another with no loose end but have no path to the star. However neat it looks, it is wrong.
- Facing endpoints
- Two endpoints pointing at each other. They form the smallest possible isolated group, so it can never be right.
- Bridge
- A tile that turns to join two groups into one. Near the end of a puzzle the missing connection is usually a single bridge.
- Tracing the power
- Following the circuit outward from the star to see which tiles it reaches and which it doesn’t. It is the quickest way to find what is still missing.
- Spanning tree
- The mathematical name for a network that reaches every point of a grid and contains no loop. Every solved board is one.
Names and variants
- Net
- The name of the puzzle in Simon Tatham’s Portable Puzzle Collection, where it was the first puzzle written, in 2004.
- NetWalk
- The name used by versions that dress the puzzle as computers and a server, including the Gamos game of the 1990s and KDE’s KNetWalk.
- FreeNet
- A browser version by Pavils Jurjans, credited as the inspiration for Net.
- Pipes
- A common name for the puzzle on the web and on phones, where the arms are drawn as pipes.
- Locked tile
- In versions that offer it, a tile you have marked as finished so that it can’t be turned by accident. Also called a pinned tile. Rune Circuit has no lock, so you keep track yourself.
- Wrapping
- A variant in which arms may leave one side of the board and connect to the tile on the opposite side. Rune Circuit does not wrap.
- Barrier
- In some versions, a fixed wall between two squares that no connection may cross. Barriers act as hints. Rune Circuit has none inside the board.
- Unique solution
- A puzzle with exactly one finished arrangement. Some versions guarantee it. Rune Circuit accepts any arrangement that meets the rules.