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Double threats (forks): how games are really won

A single threat can always be blocked. Two threats at the same time usually cannot. That simple idea, the double threat or fork, decides nearly every game between good players.

Why one threat is not enough

When you make a four, your opponent has exactly one move that stops it, and they will play it. When you make an open three, they have two good answers. In both cases the attack is over after one reply. To win, you need a move that creates two separate threats, so that blocking one lets the other through.

The four-three

The strongest fork is the four-three: one move that makes a four on one line and an open three on another. Your opponent must block the four immediately, or you win on the spot. Then you turn the open three into an open four, and the game is over.

X plays the green point: four across (O must block at the right end) and an open three down. Next move, the three becomes an open four.

The three-three

A three-three makes two open threes with one move. Your opponent can only block one of them; the other becomes an open four. It is slightly weaker than the four-three, because a defender who has a four of their own can sometimes use it to gain a tempo and escape. Before playing a three-three, check that your opponent has no four ready.

The green point makes two open threes at once: across and down.

Preparing a fork

Forks rarely appear by accident. Good players prepare them by placing marks that belong to two lines at once. A mark at the crossing of two of your half-built lines is worth far more than a mark that only extends one. Diagonals are especially useful because many opponents watch rows and columns more closely.

Keep your marks close together, about one or two crossings apart, so several lines can meet.
Use forcing moves (fours and open threes) to make your opponent answer where you want, then play the fork.
Before your fork, count the opponent’s fours: a defender with a four can interrupt you.

Defending against forks

The best defence is to stop the fork before it exists. When two of your opponent’s lines are about to meet on one crossing, playing on that crossing yourself often kills both at once. Our guide on defending shows how to find these key points.

After each game, the Mòpyon coach marks the moves where a forced win was available. Replaying those moments is the best way to learn what a fork looks like in real games.