⬡ Pente Guide

What Is Pente?

Pente is a five-in-a-row game with a rule borrowed from the Go family: you can capture. It was devised by Gary Gabrel in the 1970s as an adaptation of the Japanese game Ninuki-renju, and its name is the Greek word for five. Two players take turns placing stones on the intersections of a 19x19 grid, and there are two ways to win — line up five stones, or capture five pairs of your opponent's stones.

That second route changes the character of the game. In Gomoku a stone, once played, is permanent. In Pente a carelessly placed pair can vanish, taking a half-built line with it, and a stone used to block a threat can be lifted off to reopen it. You have to read two kinds of threat at once, and many games are decided by a capture that breaks a line rather than by the line itself.

The Rules

• You move first with the light stones; the AI plays dark. Each turn, one stone goes on any empty intersection.
• Five or more in a row wins — horizontally, vertically or diagonally. Lines longer than five count too.
• Capture by flanking exactly two. If your new stone and one of your existing stones sandwich exactly two enemy stones in a straight line, those two are removed. This works in all eight directions, and one stone can capture several pairs at once.
• Ten captured stones wins. The counters above the board show stones, not pairs, so the target is 10.
• Moving into a flank is safe. If you place a stone that completes the pattern enemy, you, you, enemy, nothing is captured. Only the player who moves captures.
• Only pairs can be taken. One stone or three stones between enemy stones are never captured.

One difference from tournament play: competitive Pente makes the first player start on the centre point and place their second stone at least three intersections from it. This version has no opening restriction. If the board fills with no winner, the game is a draw. Picking a difficulty starts a fresh game, and there is no undo.

Core Strategy: Lines and Captures Together

Pairs are the weak point

Whenever two of your stones sit side by side in a line, check both ends. If one end holds an enemy stone and the other is empty (O X X _), your opponent captures by playing the empty end. If both ends are empty (_ X X _), the pair is safe for now, but one enemy stone at either end turns it into a capture threat that can be cashed next turn. Most lost captures come from the same move: extending a single stone into a pair directly beside an enemy stone, which hands over a threat for free. A stone can be part of a safe three horizontally and a vulnerable pair diagonally at the same time.

Split shapes

Because only pairs can be captured, the gap shape X _ X is sturdier than X X. Neither stone can be taken as part of that line, and filling the gap later gives a solid three. The split three (X X _ X or X _ X X) is just as useful: it threatens to become four, it is harder to spot than a solid three, and the gap gives your opponent no safe bracketing point. Likewise, turning a threatened pair into a three removes the threat along that line, because a sandwich of three is not a capture.

Tria and tessera

Pente players call an open three a tria and four in a row a tessera. The logic mirrors Gomoku: an open tria (_XXX_) must be answered, or it becomes an open tessera that threatens five at both ends and cannot be stopped with one block. Pente adds a second way to defend. A capture that removes even one stone from a line breaks it, and the two stones of a capture always lie along the capture direction — so to break a horizontal four, look for a vertical or diagonal pair that includes one of its stones. If that pair is flanked on one side by your stone, playing the other side takes it and the four is gone without a block.

The capture race

Captures count toward victory even when they break nothing, and the race sharpens as the numbers climb. Once a player holds eight stones, every capture threat they make is a threat to win the game and must be treated like a four. That creates a powerful double threat: one stone that both extends a line to an open three and brackets one end of an enemy pair. Your opponent can stop the line or save the pair, not both. When the opponent is the one on eight, every pair you own is a liability, so play shapes with gaps.

Turning blocks into weaknesses

A block is only as permanent as the stone that makes it. Suppose your opponent blocks one end of your three. If that blocking stone forms a pair with one of their earlier stones, and you already have a stone beyond the pair, you can capture both — removing the block, scoring two stones and reopening your line in one move.

Common Mistakes to Avoid

• Making a pair next to an enemy stone. O X X _ is a capture waiting to happen. Extend with a gap instead, or go to three.
• Blocking with a capturable stone. If your blocking stone pairs up with one of your own and can be bracketed, the block can be removed and the threat returns with interest.
• Only defending along the line. Fours and threes can be broken from the side by capturing a crossing pair. Look for that before spending a move on a plain block.
• Forgetting the count. The difference between six and eight captured stones is the difference between a nuisance and a winning threat. Check the counters every few moves.
• Playing in tight clumps. A dense blob of stones creates pairs in many directions at once. Spread shapes give you the same lines with far fewer weaknesses.

Playing Against Our AI

The PlayVersusAI Pente engine follows a fixed order on every level. If it can win at once, by making five or by taking the pair that brings it to ten, it does, even if you also have a four. If you threaten to win next move, it picks the reply that leaves you the fewest winning points, which may be a block or a capture that breaks your line. Only then does it judge the position, telling open twos, threes and fours from blocked ones, spotting split shapes and double threats, and weighing captures, capture threats and the risk of forming a pair that can be bracketed.

Its blind spot is length: long plans stay invisible until they are close.

Frequently Asked Questions