GOMOKU This category is only Gomoku as this site plays it: a 15 by 15 board, one stone per turn, and a win that is exactly five consecutive stones. Six in a row does not win, and there are no forbidden moves.
The notes below are informational. They use the same rule as the live game. Nothing here links away from this site.
The basic idea
Gomoku is a two-player game on the intersections of a grid. Black places the first stone. White answers. A stone, once placed, stays where it is. Nobody captures, and nobody moves a stone that is already down. The game ends when one player completes a line of exactly five of their own stones, or when all 225 intersections are full and nobody has done that.
A line can run horizontally, vertically, or on either diagonal. The five stones must be consecutive. An empty intersection in the middle breaks the line, even if stones sit on both sides of the gap. A sixth stone added to an already finished five does not create a win and does not cancel a five that was completed earlier in the same line.
People also call related games five in a row or Gobang. Those names do not guarantee the same details. Some boards are 19 by 19. Some rules treat six in a row as a win. Renju adds opening procedures and restrictions that mostly limit Black. This category does not mix those rule sets in. If a sentence here describes a win, it means exactly five on this board.
The shapes in this category
Almost every useful conversation about a position names a shape. The names below are the ones the other articles in this category use. They are not extra rules. They are ways to count empty ends and gaps.
- Open three. Three consecutive stones with an empty intersection at each end, such as
· ● ● ● ·. It is a developing threat, not a win. The defender still has time to interfere before it becomes four. The open-shapes article shows the threat and the defense. - Open four. Four consecutive stones with an empty intersection at each end, such as
· ● ● ● ● ·. Blocking only one end still leaves the other end as a win. One defensive stone cannot stop an open four unless the defender is winning immediately somewhere else. - Closed four. Four consecutive stones with one end already blocked, such as
○ ● ● ● ● ·. There is one winning point. If it is your turn and that point is empty, you can take it. If it is the opponent's four, that point is the block. - Broken four. Four stones that would be five if one gap were filled, such as
● ● · ● ●or● ● ● · ●. The gap is the winning point. Counting only solid blocks of stones misses it. The open-shapes article treats this separately from the open four. - A line that cannot grow. Stones pressed against the edge, or against the opponent, may look long and still have no empty intersection that makes five. Adding another stone to that line spends the turn. The beginner-mistakes article shows this next to the move that actually matters.
How a turn works
Use the same order on every turn, including the first moves, when the board looks empty and the order feels unnecessary. The strategy article expands the same checklist. The attack-or-defend article runs it on one position with three candidate moves.
- Look for your own win. Trace the row, the column, and both diagonals through your stones. If an empty intersection completes exactly five, that is the move. Take it before you build anything else.
- If you have no win, look for the opponent's win. A closed four needs one block. An open four cannot be stopped by one block. Two separate winning points usually means the position is already lost if it is not your win this turn.
- If neither side can finish immediately, make a threat that forces a reply. Extending an open three toward an open four is the usual example. Then imagine the defensive stone and check the board again. A threat with no continuation only hands the opponent the next free move.
- Prefer a stone that does two jobs: it lengthens your line and takes away an extension of theirs, or it aims at two directions at once. Under this site's rules a double threat is legal for both colors. Renju sometimes forbids particular double threats for Black. Those bans are not in force here. The exact-five article states that difference without adding a second category.
- Place one stone on an empty intersection. In the browser game, click or tap the intersection, or focus the board and use the arrow keys and Enter. Occupied points cannot be reused. After the stone is down, the same five checks run again for the player who just moved.
What this looks like in an ordinary game
- You have four stones in a row and one empty end. The other end is already a white stone. It is your turn. The empty end is the whole story of the position. Playing anywhere else gives White the chance to occupy that end, and then your four no longer wins.
- White has three stones with both ends empty, and you have a quiet developing move you like. The open three is not a win yet. You can still play your move, but you should know which of White's ends you will answer on the next turn. Ignoring both ends for two turns is how an open three becomes an open four.
- A diagonal of three black stones sits under a horizontal line you have been watching. The newest white stone does not touch your row. It does touch the diagonal. Counting only rows and columns is the miss described in the beginner-mistakes article.
- The board is nearly full near a corner. Four black stones run into the edge. There is no second end to threaten. The edge has already done the defender's work on that side. A fifth stone on the open side would still win, and a stone added beyond the edge is impossible.
- Both players have threats, and you are choosing between a block and your own four. Play the win if you have one. If you do not, play the block. The attack-or-defend article puts those two choices, plus a quiet third move, on the same diagram so the next position is visible.
- You want to practice the count without a ranking on the line. Computer mode and same-screen mode do not change the leaderboard. Online matches do. The rules article separates those modes, the 90-second online turn, and what a resign does to a streak.
Why the exact-five rule matters
- A line of six is a legal placement and not a win. Advice written for freestyle Gomoku, where a longer line still wins, will tell you to play moves this site does not reward.
- Black is not restricted. A double three or a double four is allowed. Advice written for Renju will tell you those shapes are forbidden for the first player. Following that advice on this site gives away legal moves.
- There is no tournament opening protocol on this board. The first stone does not have to be the center, and neither player swaps colors after a set of opening stones.
- Defense is earlier than it feels. An open four is already too late for a single block. The useful defensive turn is the one that stops the open three from becoming that four, or that fills the gap in a broken four.
- The problems page is the check. Each problem is Black to move, and the winning intersection is one square, not a general idea. After the articles, the problems ask you to find that square and then show the answer.
Articles in this category
One category, Gomoku. These pages stay on the same rule set. They are not a second topic, and they do not replace the game.
- Five mistakes beginners make — a bad move and a better move, and what the board looks like after each.
- Open three, open four, and broken four — the threat and the defense for each shape.
- Attack or defend first — one position, three candidate moves, and the result of each.
- Exactly five versus Renju — six in a row is not a win here, and nothing is a forbidden move.
- Problems and answers — Black to move. Find the square that wins now.
- How a game is played on this site — the board, the three modes, timers, and streaks.
- A move checklist — immediate wins, blocks, forcing threats, directions, and the edge.
Closing
Read a shape, then play the turn in the order above: your win, their win, then a threat you can follow. The articles in this category repeat that count on diagrams. The game on the home page uses the same board and the same exact-five rule, so a line you count here is a line you can finish there.
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