Net

Rotate the grid squares so that they all join up into a single connected network with no loops.

Squares connected to the middle square are lit up. Aim to light up every square in the grid (not just the endpoint blobs).

The game mode says where the network may run:

• Bordered: The network stays inside the grid.
• Wrapping: The network may run off one edge of the grid and come back on the opposite one.

Controls

On a touch screen, a tap does what a click does, and a long press what a right-click does (more ways to right-click). A key the puzzle’s controls show as a button can be pressed there instead of on a keyboard.

Click a square to rotate it anticlockwise. Right-click it to rotate it clockwise.

With the keyboard, the arrow keys move a cursor around the board. Enter (or A) does what a click does to the square under it, and Space (or D) what a right-click does. Press F to rotate the square under the cursor half a turn, or click it twice. Press S to lock the square under the cursor once you think it is correct, so you don’t rotate it by accident, or unlock it again, or, in notes mode, click the middle of the square.

To move which square the network is lit from, press the Source key on the keypad and then tap the square, or press Ctrl and an arrow key. On a wrapping grid, drag in the margin around the grid, or press Shift and an arrow key, to scroll the whole grid. The Jumble key, or J, jumbles every unlocked square to a random rotation.

Notes

You will often know what crosses the side between two squares before you know which way either of them turns: a corner piece on the edge of the grid points inward whichever way it turns, and two dead ends can never face each other. Notes lets you write that down. Press the Marks key on the keypad, or P, to turn notes mode on, the same way as in every other puzzle that takes notes; a small pencil shows at the top right of the board while it is on, and pressing it again turns it off.

In notes mode, click near the side two squares share to note that a wire crosses it (a short pencil stub across the side), or right-click (on a touch screen, a long press) to note that no wire does (a pencil ×). Doing the same again takes the note off. Click the middle of a square instead to lock it, or to unlock it again; outside notes mode, S does the same at the cursor. Either can be dragged: keep the button down and the sides, or the middles, you pass over get the same. From the keyboard, press Enter or Space on one square, move to the square beside it, and press Enter to note a wire between them or Space to note none; Escape lets go of the first square. A side with a wall on it needs no note.

A note or a lock that turns out to be wrong shows in red when you check the board.

Hints

Hint explains the next step rather than simply making it. It reasons only from your locks, your notes and the walls: a square you have turned but not locked counts as unknown, however it is turned. So lock a square once you are sure of it, and the hint carries on from there. If a lock or a note is wrong, it asks you to fix the highlighted mistakes first.

Each step either notes a side or turns a square and locks it. The hint calls a square with one wire a dead end, two in a line a straight, two at a right angle a corner, and three a T; a note is one of your side notes, and a lock a locked square.

• A ring marks what the step decides: the square to turn and lock, or the side to note, with the note the step places drawn inside its ring.
• An outline marks what the step reasons from: the notes and locks a way of turning would contradict, the square whose every way of turning agrees about the ringed side, or a square beside it that a way of turning would leave with no way to turn.
• Stripes mark the squares a way of turning would close a loop through, or seal off from the rest.

The ideas it teaches:

• Fit the sides you know. A square can only turn to ways that carry a wire across every side noted as crossed, none across a wall or a side noted as empty, and match each locked square beside it. When only one way is left, lock it; when every way left agrees about a side, note it.
• No loops. A way of turning that would join two squares the known wires already join would close a loop.
• Nothing sealed off. A way of turning that would close a group of squares off, with no wire left to lead anywhere else, cannot be right unless the group is the whole grid: two dead ends facing each other are the smallest case. The wire need not be drawn yet. A way of turning that leads only into squares where the wire must stop, however they turn without closing a loop, seals them off just the same. Picture the square turned that way while you follow its wire: the squares the wire runs into have to fit it, and a loop through it is still a loop.
• No square left stuck. A way of turning that would leave the square beside it no way to turn cannot be right. Every way the square beside it has either fails to fit, or closes a loop through the squares the hint stripes. The hint looks for this only where nothing simpler is left.

When a square has to turn before it can be locked, the hint turns it and then locks it, as one step.

On an Unreasonable board there comes a point where none of this settles a square or a side. The hint then says that nothing further follows by deduction instead of choosing for you. Save your position, lock a square with two ways left one way, and carry on: if it was wrong, some square a few steps later has no way left. The hint carries on from whatever you lock.

Net parameters

These parameters are available from the ‘Custom type…’ option on the ‘Type’ menu.

Width, Height

Size of the grid in squares. At least one of them must be more than 1, and a wrapping grid cannot be exactly 2 squares wide or high, since such a grid can never have just one solution. Each must be at least 1.

Game mode

Which puzzle to play: Bordered or Wrapping. The rules of each are at the top of this page.

Barrier probability

The share of the places where the finished network has no wire that get a barrier drawn across them. At 0 there are no barriers inside the grid; at 1 every such place has one, which gives away a lot about the solution. It must be between 0 and 1.

Difficulty

Determine the difficulty of the generated puzzle; see what the names mean. An Easy puzzle can be finished one forced square at a time: there is always a square with only one way left to turn, or a side every way left agrees about. An Unreasonable one has a single solution that those steps stop short of, so somewhere you have to try a square one way and see what follows. The Hint button stops where the forced squares do.

More help

• Features every puzzle shares: hints, checking your work, checkpoints, playing by touch
• Help home