Gomoku Online — Five in a Row

Threats are the whole game

Beginners try to make five. Stronger players make threats — shapes that will become five unless the opponent answers immediately — and win because the opponent eventually runs out of answers.

Open three. Three of your stones in a row with empty points at both ends. Left alone it becomes an open four next move, which is unstoppable, so an open three almost always forces a reply. It is the cheapest way to take the initiative.

Four. Four in a row with one open end. Your opponent must block that end this move or lose. A four is absolute, but it forces only one reply, so a single four wins nothing by itself.

Open four. Four in a row with both ends open. There are two winning points and your opponent can block only one. If you can build an open four, the game is already over.

Broken three. Three stones with a gap. It threatens to become a four by filling the gap, and beginners routinely miss it because the stones are not adjacent.

The double threat

Every Gomoku game is decided by a double threat — one move that creates two separate threats at once. Your opponent answers one; the other wins.

The common forms are the double four, where both fours must be blocked and only one can be, and the four-plus-open-three, which is usually decisive: the four forces an immediate block, and while your opponent answers it the open three matures into an open four.

This is why placing stones so they share lines matters more than placing them near each other. A stone contributing to a row, a column and a diagonal is doing three jobs; a stone that only extends one line is doing one.

Defence: count the forcing moves

Under pressure, do not simply block the most recent stone. Ask which of your opponent’s shapes are forcing: a four must be answered now, an open three almost always must, a plain three can often be ignored. Blocking a harmless three while an open three ripens elsewhere is the most common way to lose.

Where you can, block on the side that also builds something of your own. Defence that creates a threat forces your opponent to stop attacking, and that is how you take back the initiative.

Black is better, and freestyle does nothing about it

Gomoku has been solved: on a 15×15 board under freestyle rules, the first player wins with perfect play. Tournament formats correct this with opening restrictions or a swap rule, where one player proposes an opening and the other picks a colour. Play Lounge uses plain freestyle with no restrictions, so Black keeps the advantage.

In a casual game this matters less than it sounds, because nobody plays perfectly — but it is worth knowing, and it is a good reason to alternate who goes first across a series rather than playing a single deciding game.

Practical opening advice

Start near the centre. A stone in the middle sits on four lines — row, column and both diagonals. A stone near an edge has fewer directions to grow, and lines that run off the board are dead weight.

Keep your stones connected but not cramped. Stones two points apart often work better than adjacent ones: they leave room for the gaps that make broken threes, and they cover more of the board.

As White, do not only block. Answering every Black move without building anything hands over the game. Look for blocking points that also start a line of your own.

Watch the diagonals. Diagonal threats are the ones people miss, because the eye tracks rows and columns first. Most surprise losses come from a diagonal.

The same game under different names

Gomoku comes from the Japanese gomokunarabe, “five points in a row”. It is the same game as Gobang, Five in a Row, Chinese Wuziqi (五子棋), Korean Omok (오목) and Vietnamese Cờ caro. If you learned it on squared paper at school, you already know it.

Renju is the tournament version: Black is forbidden from making a double three, a double four or an overline, which cancels most of the first-move advantage. It is a stricter, more studied game — and not what is played here.

Gomoku is not Connect Four, where pieces fall to the bottom of a column and four wins. Gomoku’s board is far larger, stones stay exactly where you put them, and you need five — which makes it the deeper of the two by some distance.