Vs AI · 7 min

How to Beat the Computer on Hard Difficulty in Gomoku

The AI is strong at blocking an immediate win and at scoring stone patterns. Its weakness is that it can only answer one threat per turn — so give it two.

What is the Caro Classic AI thinking?

The AI takes an immediate win if one is available. If not, it blocks your winning move, then scores attacking and defensive patterns around stones already on the board. It handles open threes reasonably well, but it does not look as far ahead as an experienced human player. That means it can be beaten by a plan that creates danger in more than one place, rather than by trying to outplay it in a single line.

Tactic 1: create two threats

Do not attack along a single row. Build two open threes in different directions, or an open three and a four at the same time. The AI can only block one of them, and the other should still have a path to five in a row. Before you commit, check that both threats are genuinely alive: a line that is already closed at both ends is not a threat, no matter how long it looks.

Tactic 2: force the AI to defend

Place stones so that the AI has to respond, then use its blocking move as a stepping stone for your second line. The more you pull the AI towards one side of the board, the emptier the other side becomes. This is not about tricking the computer with a hidden rule; it is about making the cost of defence add up until it cannot cover everything.

Tactic 3: attack on both wings

Open shapes on two sides of the board instead of concentrating everything in one cluster. The AI tends to focus around the nearest stones, so the distance between two groups makes it harder for the computer to defend both at once. Keep each group strong enough to survive on its own, and look for the moment when the AI commits to one wing and leaves the other underdefended.

Tactic 4: use Undo to learn

When you lose, press Undo to return to the exact position before the mistake. Try a different move and watch how the AI responds. This is the fastest way to practise, because you do not have to replay the whole game to test one idea. Over time you will start to recognise the positions where the AI's single-threat defence breaks down.

Mistakes that lose to the AI

Attacking along only one row.
Blocking late, after the AI already has four.
Placing stones too far from your main group.
Ignoring both ends of a line.
Changing direction constantly without completing any shape.

Practice

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