A single threat can always be blocked. So a win requires a position where two threats appear at once, and getting there requires moves your opponent has no choice about.
The forcing move
A forcing move creates a threat that must be answered immediately — a four, or an open three when the opponent has nothing stronger. While they are forced to respond, you choose where their stone goes, which means you are effectively placing stones for both sides.
That is the key insight. Forcing moves let you arrange the board. Each one costs you a threat, but it buys you control over the shape.
The four-three
The most common winning combination. One stone creates a four in one direction and an open three in another. The opponent must block the four — it threatens five immediately — and while they do, the three becomes an open four, which cannot be stopped.
The three-three
One stone creating two open threes. Each would become an open four, and only one can be blocked. It is just as decisive as a four-three, though slower — the opponent has one more move to find a counter-threat of their own.
Because of its strength, three-three is forbidden for Black in Renju rules. Free-style gomoku, which is what this board plays, allows it.
Building the combination
Winning positions do not appear spontaneously. They are built by placing stones that belong to two lines at once, well before the threats are visible. The practical method:
- Establish two or three stones in an angled cluster, not a straight line.
- Identify an empty intersection where two of your lines cross. That is your target point.
- Use forcing fours elsewhere to gain moves without letting the opponent build.
- Play the target point when both lines are one stone short.
Work backwards from the target
Pick the intersection you want to play on, then ask what each of the two lines through it needs. That turns a vague plan into a checklist.
Calculating a sequence
Before starting a forcing sequence, read it to the end. Each forcing move has exactly one reasonable reply, so the calculation is narrow — it is a line, not a tree. What you must check is that the opponent's forced replies do not accidentally create a threat of their own, which happens more often than you would expect.
If any of their forced blocks gives them a three, the sequence may rebound. Check every stone they are made to play, not just your own.
Defending against combinations
The defence is positional, not reactive. Since combinations need a crossing point, occupy crossing points early. When your opponent has two twos aiming at a common intersection, taking that intersection costs one move and defuses several turns of planning.
Practising
Set the difficulty to club and play until you lose, then undo three or four moves and find the point where the combination became unstoppable. It is almost always earlier than it feels — typically the move that created the second direction, not the move that created the threat.