Beginners attack with a single line: they push three, four, and hope. Intermediate players attack with a combination: one move that makes two threats. Strong players think one level higher still. They build a network — several lines crossing at several empty points — so that the defender cannot stop every combination, however well they defend.
This article explains how networks work and how to build one.
One line is never enough
A single line, however long, can always be blocked. An open three becomes a closed three with one defender move; a closed four is stopped with another. A lone attack runs out of steam after two or three forcing moves.
Wins come from crossing lines. When two of your lines meet at an empty point, a single mark there can create two threats — a four-three or a double three. The defender can answer only one.
One crossing is also not enough
Here is the step many players miss. A single crossing point is visible. A decent defender will see it and occupy it before you use it, often with a quiet move that also builds their own shape. Your combination disappears.
The answer is to have two or three crossing points at once. The defender can take only one per move. If you have two crossings ready and it is your move, one of them survives.
The important word is different. Two crossings that share the same line are fragile: a single defender mark on that shared line can damage both. Crossings built from four separate lines are robust, because the defender has to spend a separate move on each.
How networks grow
A network grows from the same quiet moves that build good shape, but with one extra question in mind: does this move create a new crossing point?
Good network-building moves typically:
- extend one of your lines toward another of your lines, so they will meet at an empty point;
- place a mark that sits on two of your potential lines at once, creating twos in two directions;
- add a mark near an existing crossing, so that the crossing becomes a double threat rather than a single one.
Imagine your marks as a small cluster with lines radiating from it. Each new mark should add a spoke that crosses another spoke somewhere empty. After a few such moves, the empty points between your spokes become crossing points — and each one is a potential combination.
Using forcing moves to complete the network
Sometimes you have one crossing ready and a second one almost ready. Rather than a quiet move (which gives the defender time to take your first crossing), use a forcing move that also completes the second crossing. The defender must answer your threat, and when the smoke clears you have two crossings and it is your move.
This is the heart of strong attacking play: forcing moves are not just threats; they are free building moves, because the defender's reply is predictable and your forcing mark stays on the board.
Reading the defender's options
When you have a network, count the defender's resources:
- Can they occupy all your crossings? If you have more crossings than they have moves before your combination, you win.
- Can they interrupt with fours? Each four they make forces you to answer, giving them extra moves. If they have many fours, your network needs more crossings or more forcing power.
- Do their forced replies land on your crossings? If your threats send their marks exactly onto your own crossing points, you are destroying your own network. Choose threats whose replies land elsewhere.
Defending against networks
The defence is the mirror image. As the defender:
- Watch crossings, not just lines. A line of two is harmless; two lines of two meeting at an empty point are not.
- Occupy the most valuable crossing — the one closest to becoming a four-three — with a move that also builds your shape.
- Use your fours to gain tempo when the attacker has more crossings than you can handle.
- Kill lines permanently under blocked ends: a crossing needs both lines alive, so killing one line kills the crossing.
A practical network checklist
Before each quiet move in the middle game, ask:
- Where are my current crossing points?
- Does this move create a new crossing, or strengthen an existing one?
- Does it also break one of the opponent's crossings?
A move that answers yes to two of these is usually excellent.
Networks under blocked ends
Under Vietnamese caro rules, networks matter even more, because individual lines die more easily. A network of four or five lines crossing at several points is much harder to dismantle than a pair of lines. At the same time, each line in the network must have genuine room: check that none of the lines your crossings depend on is already walled in at one end. See attacking under blocked ends.
A network in words
Here is how a network typically forms over a few moves. X has a row two in the centre. X adds a mark diagonally below it, starting a column two that points at the square just right of the row two — the first crossing. The defender sees it and takes that square.
Instead of rebuilding the same crossing, X adds a mark above the row two on the other side, starting an anti-diagonal two that crosses the row's left extension. That is a second crossing, on different lines. At the same time the new mark forms a small column with an older X mark, pointing at a third crossing further up. The defender can take only one of these points. X uses the other for a double three, or waits one more move to turn it into a four-three.
Notice that X never pushed a single line past three during this phase. The attack was built entirely from twos and crossings, which is why the defender had nothing obvious to block until it was too late.
Practice
Play the computer on the home board with a single goal: before attacking, have two crossing points ready. It will slow down your attacks at first. Then watch how often your combinations succeed compared with before. Replay your games from your account and, for each win, count how many crossing points you had when the winning combination started.
Frequently asked questions
What is an attack network in gomoku?
A group of your lines crossing at several empty points, so that you have more than one possible combination at once.
Why is one crossing point not enough?
Because the defender can see it and occupy it before you use it. Two or more crossings cannot all be stopped in one move.
How do I create more crossing points?
With quiet moves that extend your lines toward each other, and with forcing moves whose marks complete a second crossing.
How do I defend against a network?
Occupy the most dangerous crossing points, use your own fours to gain tempo, and under blocked ends kill lines permanently.
