Gomoku

五目並べ · Five in a Row · 五子棋

Black to move

0Black

0White

0Draws

Opponent

Warn me about threats Show move numbers Show coordinates

Rules

Players take turns placing one stone on an empty intersection. Black moves first. Stones never move and are never captured.
The first player to make an unbroken line of five stones — across, down or diagonally — wins.
Five or more (freestyle): a line of six or longer also wins. Exactly five (standard Gomoku): a line of six or more doesn't count.
If the board fills up with no five, the game is a draw.

Tips for beginners

Block open threes. Three in a row with both ends empty becomes an unstoppable open four next move. Block it at once.
A four must be answered. Four in a row with one gap left forces your opponent to block — use this to take the lead.
Win with double threats. A move that makes two threats at once (four-three, or three-three) can't be stopped by a single block.
Stay connected. Place stones near your others so each new stone helps several lines at once.
Turn on Warn me about threats and the board marks the points where your opponent is about to win.

How the computer plays

Shape reading. For every empty point it knows, in each of the four directions, whether a stone there would make a five, an open or closed four, an open or closed three, or a two.
Threats first. It always wins when it can, always blocks a four, and answers an open three by blocking or counter-attacking with a four.
Forced wins. On Medium and Hard it searches chains of fours (VCF) that the opponent must answer and that end in a five.
Look-ahead. It then searches the most promising moves several turns deep with alpha-beta search. Hard looks furthest and checks that its move doesn't let you start a winning chain of fours.
Levels. Easy plays by feel and sometimes misses an open three. Medium thinks for about a second, Hard for up to four.