人機五子棋

Gomoku vs AI: rules, tactics and practical play

Play black first and race three levels of computer opponent to five in a row. This guide reflects the controls and win conditions in the current browser build. It is reviewed by the PocketJoy game-testing team and maintained by Long-Term New Media Limited.

Rules and winning conditions

You take black and move first against the computer on a 15×15 board. Stones are placed on the line intersections and, once played, can neither be moved nor captured — the fundamental difference from go and chess, since the board only fills up and the position only accumulates in one direction. Five in a row horizontally, vertically or on either diagonal wins. The most recently played stone is outlined in pink so you can always see where the computer just moved, which matters on a board this large. If the grid fills with no line of five the game is drawn, though that is rare in practice. Three computer difficulty levels are available, with the hardest actively building double threats. The status line reads either your turn or a thinking notice, and wins and games played are recorded on your device.

Match strategy

The two shapes that matter are the open three and the four, and understanding them is effectively learning the language of the game. An open three is three stones in a row with both ends free; left alone it becomes an open four, which can make five at either end and cannot be stopped, so an opponent's open three must be answered immediately. A four is four in a row with one end able to make five, which forces a block — but once blocked you have lost the initiative, so a four borrows time rather than winning, and is only worth playing when it feeds into another threat. The standard winning method is a double threat: two open threes at once, or a four and a three together, so your opponent cannot answer both. In practice you look for an intersection where a stone contributes to potential threes in two directions, usually where existing diagonals meet. Black's first move is a real advantage, so keep your early stones near the centre where each contributes to several directions, rather than scattering them. On defence, learn to block at the open end: a three already blocked at one end is a dead three and poses little danger, so prioritise genuinely open ones.

Frequent errors

Beginners typically focus on their own line and notice the opponent's open three only when it is too late. Before every move, check their shapes for a three in a row or a broken three with one gap; that scan matters more than advancing your own attack, and broken threes are especially easy to miss because they are visually discontinuous while being exactly as dangerous as a solid one. The second mistake is assuming a long straight line is strong. Stones committed to one direction are easily blocked at both ends, whereas the genuinely threatening shapes are intersections that can grow in two or three directions, so the question to ask is how many potential fives a stone participates in, not how long your line has become. The third mistake is always blocking directly beside the opponent's stones. Blocking slightly further out, at the point their line would need to extend through, sometimes develops your own shape at the same time and answers attack and defence in one move. The fourth is calculating only one move ahead on the hard setting, where the computer builds multi-move combinations and a purely local response often helps complete a double threat it planned several moves ago.

Who it's for

Well suited to people who like board games but are short on time. The rules are far simpler than chess or go and take a minute to learn — no piece types, no differing moves, no captures — yet attack and defence swap constantly and a single careless move can lose the game, which keeps the tension high. The game is also solved mathematically: in 1993 Victor Allis proved that in free-style gomoku the first player, black, wins with correct play, which is precisely why competitive renju adds forbidden-move restrictions for black to restore balance. This implementation uses free rules, so playing black gives you a theoretical advantage and the question is whether you can convert it. A game usually runs five to ten minutes, faster than most board games, and the hard difficulty actively builds double threats.

Feature highlights

Three computer difficulties can be switched from the sidebar at any time without restarting, with the hard level building double threats rather than merely responding to your lines. The record panel accumulates wins and games played separately, and having both lets you judge your long-term rate rather than your impression of the last few games. The status line always reads either your turn or a thinking notice, so you know whether to act and will not click repeatedly while the computer calculates. After each computer move its stone is outlined in pink — a design that matters especially on a 15×15 board, since without it you would have to scan the grid to find the latest play, and missing the opponent's last move is a common way to lose. The result dialog distinguishes wins, losses and draws with a brief comment, such as a suggestion to adjust your strategy after a loss. A restart button is always available.

Controls and match records

Tap an intersection on the board to place a stone, identically with mouse or touch; occupied points do not respond, so an existing stone can never be overwritten. On a phone the board scales to a comfortable one-handed size, and although 15×15 intersections sit closely together, the tap targets are tuned so neighbouring points are not caught by mistake. A restart button is available at any point rather than only once the game is decided. Your record lives in the browser's local storage and survives closing or refreshing the page; there is no account system, nothing is uploaded to any server, and clearing browser data removes the record. The language button switches everything — prompts, status line and result comments — between Traditional Chinese and English instantly, without a page reload and without interrupting the game in progress. Once the page has loaded, the game itself needs no network connection.

Rules Q&A

For a structured look at threats, read Gomoku Threats: Open Threes, Fours and Double Attacks.

Reviewed by the PocketJoy game-testing team · Operated by Long-Term New Media Limited · hklongtermad@gmail.com