How to Read a Gomoku Board: Scanning Four Directions, Counting Lines and Spotting Danger Before It Becomes a Four

Strong gomoku players do not have better eyes than beginners. They have a method — a routine for looking at the board that makes sure nothing important slips past. Once you have the routine, it runs almost automatically, and your mind is free to think about plans instead of worrying about what you might have missed.

This article teaches that routine in four steps.

Step 1: Start from the newest mark

Positions change one mark at a time. Every new threat on the board involves the mark that was just placed — so that is where you start. You do not need to re-examine the whole board after every move; you need to examine the lines through the newest mark.

Every point sits on exactly four lines:

the row (left–right),
the column (up–down),
the main diagonal (bottom-left to top-right),
the anti-diagonal (top-left to bottom-right).

Step 2: Count each line

For each of the four lines, count the opponent's marks near the new mark. The reliable way:

From the new mark, move outward in one direction. Count marks until you reach an empty point or an enemy mark.
If you reached an empty point, look one more point beyond it. If there is another of their marks there, note the gap — this is a broken shape.
Do the same in the opposite direction.
Note what sits at each end: empty, your mark, or the edge.

It sounds slow written down, but after a few days it takes a second or two per line.

O has just played g7. On O's own lines through g7 nothing is dangerous yet, but the move quietly blocked one end of X's diagonal three h8–j10. Only k11 (highlighted) is still open for X.

The diagram shows why scanning your own lines matters too: the opponent's "quiet" move may have been a block you did not notice, changing which of your plans still work.

Step 3: Classify what you found

Once you have counted, put each line into one of a few simple categories:

Five: game over.
Open four: four in a row, both ends empty. Unstoppable unless you win first.
Four: four marks with exactly one way to complete five (one end blocked, or a single gap). Must be answered immediately.
Open three: three in a row (or a broken three) that can become an open four in one move. Must usually be answered.
Closed three: three that can only become a closed four. Not urgent on its own.
Two: two marks with space around them. The raw material of future threats.

The details of each shape are covered in open and closed threes, open four and four and broken threes.

Step 4: Decide by urgency

Now rank everything you found — for both players — by urgency:

Your own five. If you can win, win.
Their four. You must block it now.
Your own four that also creates a second threat. This may win.
Their open three. Block it, unless you can make a four first.
Your own open three or double threat. Now you can attack.
Everything else. Build shape, prefer points that help two of your lines.

This order solves most decisions in a real game. Beginners mostly go wrong by doing item 5 when item 2 or 4 is on the board. The full reasoning is in threat priority order.

Practising the routine

The fastest way to build the habit is to practise it slowly at first:

Play the easiest computer level on the home board.
After each computer move, say the four directions out loud and name what you see on each: "row, nothing; column, a two; diagonal, their three, open; anti-diagonal, nothing."
Only then choose your move.

It feels silly for the first few games. After twenty games you will do it silently in a second, and you will notice threats you used to miss.

Scanning your own position

The same routine works for attack. After your own move, scan the four lines through your new mark and ask: what does this mark threaten next? Often you will discover that your move created a second line you had not planned — an unexpected double threat. Strong players find many of their best moves this way: not by planning a combination from scratch, but by noticing what their pieces already threaten.

Wider scans

Every few moves, especially when the game gets crowded, do one wider scan: look over the whole active area and ask where each player has two or more lines crossing near an empty point. Those crossing points are where double threats are born. Knowing them in advance means you are never surprised by a four-three.

Common scanning errors

Counting a gap as a break. A pattern like X X _ X is not "two and one" — it is a broken three, one move from four.
Forgetting the ends. A three blocked at one end is much less dangerous than an open three. Always note both ends.
Only scanning when worried. The dangerous moves are the quiet ones. Scan every move, not just when you feel threatened.

A worked example of the routine

Suppose the opponent has just placed a mark in the middle of a busy area. Run the routine:

Row: two of their marks with a gap and then a third — a broken three. Is it open at both ends? If yes, it is urgent.
Column: a single mark next to yours. Nothing to worry about.
Main diagonal: two of their marks, one end blocked by you. A closed two — ignore for now.
Anti-diagonal: empty around the new mark. Nothing.

Conclusion: the broken three on the row is the only real threat, and it can become an open four in one move by filling the gap. You block — usually in the gap itself, because that kills the shape most completely. Then, and only then, you look at your own chances.

The whole routine took four quick glances. That is the point: a method replaces vague worry with a short, reliable checklist.

Why a routine beats talent

Players who "just see" threats are not doing anything mysterious. Their eyes follow the same four directions every time because they have done it thousands of times. You can shortcut years of experience by doing it deliberately until it becomes automatic. Nobody is born with gomoku vision; everyone who has it built it one scan at a time.

Frequently asked questions

Do I really need to check all four directions every move?

Yes, for the opponent's last move. It takes a second or two once it becomes a habit, and it prevents most losses.

Which direction do beginners miss most?

The diagonals, especially the anti-diagonal (top-left to bottom-right).

How do I get faster at reading?

Practise the routine slowly against the easiest computer level. Speed comes naturally after a few dozen games.

Should I scan my own moves too?

Yes. Scanning your own new mark often reveals threats you created without planning them.