Five in a row, from the first stone五目の基本

The game is about threats, not lines

Nobody wins by quietly building a five. A five is the end of a sequence of threats the opponent had to answer, each one leaving them a little less choice. Think in threats and the board starts to read itself.

A four (四) is four in a row with at least one open end: it must be blocked at once or it is five. An open three (活三, live three) is three in a row with both ends open and room beyond: it must be answered now, because next move it becomes an open four (活四), which has two ends to block and only one stone to block with. That is the whole ladder: three forces, four forces harder, open four wins.

The shapes that win

• Four-three (四三): one stone makes a four and an open three at once. The four must be blocked; the three becomes an open four. This is the standard winning shape, and in Renju it is the only double black is allowed.
• Three-three (三三): one stone makes two open threes. Whichever is blocked, the other becomes an open four. Forbidden to black in Renju and to both in Omok, which tells you how strong it is.
• Four-four (四四): two fours at once. Unblockable. Forbidden to black in Renju.
• A VCF, victory by continuous fours (四追い), is a sequence where every move is a four and the last is a four-three or a double. Because every move forces, the opponent never gets a free stone. Look for it whenever you have two or three stones near each other and the opponent has none.

Tempo and the free stone

The player who makes a threat chooses where the reply goes. The player who answers gets nothing for it. So the question after every move is: does this stone force a reply, and if not, what does the opponent get to do with their free stone?

Defend with a stone that also threatens. A block that makes your own three is worth two moves. A block that makes nothing hands the initiative straight back.

The opening

• Black's first stone belongs in the centre; every line through tengen (天元) has the most room.
• White's first stone goes adjacent or diagonal to it. Too far away and black builds unopposed; too close and white gets tangled.
• Plain Gomoku is a known black win with perfect play, which is why the serious rule sets restrict black (Renju), swap colours (Swap2) or push black's second stone away (Pro). If you play the plain game for a game that matters, give white the first move now and then, or use an opening.

Reading

• Before you play, count the opponent's threats on the board. If there is a four, block it. If there is an open three, block it unless you have a four of your own to play first.
• When blocking an open three, block the end that leaves your stone useful, usually the end nearer your own stones.
• A line with an enemy stone at one end is a dead three: it can become a four but never an open four. Do not spend moves answering it until it is a four.

Misère Five: losing on purpose

• Making five loses, so a four is a threat against its own maker: the opponent's task is to leave you nothing but the fifth point. Keep your lines short and broken, and force your opponent's to grow.
• Parity decides the end. The board fills, and whoever is forced to complete a five loses; a full board with no five goes to the opener. Count the safe points late in the game as you would in Notakto.