How to Win Gomoku: Strategy for Forks, Threats and Defense

The shapes you need to recognize

Every gomoku plan is built on forcing moves: moves your opponent must answer. The most important one is the open three, three stones in a line with both ends empty, so that one more stone creates an open four. A split shape like X X _ X counts as an open three too, as long as both outer ends are free. Players who only watch for three stones touching each other lose to split threes all the time.

A closed three has one end blocked by an enemy stone or the board edge. Adding a stone only produces a four with a single winning point, which your opponent can stop with one move. Closed threes are not immediate threats, but they are valuable raw material for later forks.

A four is any shape that becomes five on the next move. A closed four must be blocked at once. An open four has two winning points and cannot be stopped, so it is effectively a win. Seen this way, gomoku is really a race to create either an open four or two threats that cannot be answered with a single stone.

• Open three: both ends free, can become an open four — must be answered
• Closed three: one end blocked, can only become a closed four — building material
• Closed four: one winning point — block it immediately
• Open four: two winning points — unstoppable

Forks that decide games: 4-3, 3-3 and 4-4

A four-three (4-3) is one move that creates a four and an open three at the same time. Your opponent has to block the four, which leaves the three free to become an open four on your next turn. The 4-3 is legal for both colors in freestyle and in renju, which is why it is the backbone of practical gomoku strategy.

A double-three (3-3) creates two open threes with one stone. The defender can only block one, so the other turns into an open four. The catch is that the defender may block while making fours of their own, seizing the initiative back. Before playing a 3-3, check whether your opponent has any material for consecutive fours.

A double-four (4-4) creates two fours at once and wins immediately because there are two points to block. On Playfulo the default freestyle rule allows 3-3 and 4-4 for both players. If you switch to renju, Black alone is banned from 3-3, 4-4 and overlines, so always confirm the rule before you plan your finishing blow.

Finishing with continuous fours (VCF)

VCF stands for victory by continuous fours. Every move you play makes a four, so your opponent has no choice except to block, and the sequence ends in a 4-4, a 4-3 or an open four. Because every reply is forced, the defender never gets a tempo to counterattack, which makes VCF the most reliable way to close out a game.

To find a VCF, treat scattered twos and closed threes as potential fours. Play the sequence out in your head: after each four, note where the blocking stone lands and whether your new stone connects to another line. If the chain ends with two threats overlapping, the VCF works. If a blocking stone happens to give your opponent a four, it fails.

VCT, victory by continuous threats, mixes open threes into the sequence. It is more powerful but riskier, because an open three can be ignored by an opponent who has a four of their own. A good habit is to look for a VCF first and only then consider a VCT.

First-move advantage and good opening shapes

Black moves first and gains a real edge from that tempo. Computer searches in the 1990s proved that on a 15×15 board, freestyle gomoku is a forced win for Black with perfect play. Humans cannot memorize those lines, but the practical lesson is simple: Black should start attacking early, and White should break up Black's shape before it grows.

In the opening, avoid building one long line. Keep your stones close together so that each new stone opens several directions at once. A common approach is to start near the center and place your second stone diagonally or one point away from the first, keeping horizontal, vertical and both diagonal lines available. The standard renju openings are all compact shapes inside the central area for exactly this reason.

Stones near the edge tend to become closed shapes, so the edge is a poor base for attack. As the defender, pushing your opponent's stones toward the edge reduces how many threats they can build. On a 15×15 board, most games are decided by the fight around the center.

Defense: what to block and which side

The priority order is clear. Block any four first, then open threes. The one exception is when you can make a four yourself and continue into a winning VCF, in which case you can ignore the opponent's three and win first. Before every defensive move, ask yourself whether you can finish the game right now.

When blocking an open three, the side you choose matters. Generally block the end where your opponent has more stones nearby, the side where the line could connect to another line after your block. Against a split three like X X _ X, filling the gap is often the strongest block.

The best defensive move also improves your own position. If there are two or three points that stop the same three, pick the one that connects with your stones to form a two or a three. That way your block doubles as preparation, and you win back the tempo.

Also watch for intersections before threes even appear. Forks are born where two lines cross, so if your opponent has twos pointing in several directions, taking the crossing point early prevents the fork from ever forming.

Building an attack step by step

Strong attacks are not sudden fours. They come from gathering material along several lines and converging on one point. Keep this order in mind and your forks will start appearing much sooner.

• Step 1: Place two or three stones close together near the center so they can extend in several directions.
• Step 2: Spread twos and closed threes across at least two directions instead of stretching one line.
• Step 3: Find the point where two of those lines would meet, and check whether a stone there makes a 4-3 or a 4-4.
• Step 4: Before playing the crossing point, make a four or two to force your opponent's blocks into known places.
• Step 5: If the crossing point is still open after those blocks, play it and complete the fork.
• Step 6: If it gets blocked, use the new stones to look for the next intersection, checking every move for enemy fours and open threes.

Common mistakes

Most lost games come from missing a threat, not from being outplayed. Removing these habits one at a time makes a visible difference.

• Extending a single line: one block kills it. Always prepare a second direction.
• Missing split threes: X X _ X is an open three. Watching only for touching stones gets you caught.
• Blocking the wrong end: a careless block lets the other end connect to a new line and become a 4-3.
• Overlooking your own win: while busy defending, you miss a four that would have won on the spot.
• Playing 3-3 without checking counter-fours: the defender blocks with fours and turns the game around.
• Aiming for banned points as Black in renju: 3-3, 4-4 and overlines are forbidden, so the planned finish may not exist.

Practicing on Playfulo

Strategy only sticks when you look for threats in real games. Playfulo gomoku runs on a 15×15 board in your browser with no sign-up, and you can pick an easy, normal or hard AI. Easy is a good place to practice building 4-3 forks yourself, while normal and hard are better for learning to defend against continuous threats.

Once you are comfortable, switch from freestyle to renju and practice attacking as Black without touching forbidden points. You can also create a room and send an invite link to play a friend under the same rule, then review together where each fork came from.