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Renju Strategy and Tips

Here is how to think about winning at Renju, split into short lessons. Each one reads on its own, and each one comes with a real position: press Try it on the board and you play the move yourself.

Spotting a forbidden move

Lesson 1

Renju is gomoku with forbidden moves added: black alone loses the instant it plays a double three (one move making two open threes), a double four (one move making two fours), or an overline (six or more in a row). White has none of these restrictions.

On this site, a point that would be forbidden is marked with an × on black's turn automatically. Tapping it shows a warning that playing it loses the game; tapping it again actually plays it there and loses. The mark only reports the ruling — it doesn't change the rules.

When you spot a forbidden point, simply play somewhere else. A shape that looks like a double three but carries no × mark is safe to play — that case is covered in the next lesson.

A double three that isn't

Lesson 2

The double-three rule has an exception. A line only counts as a 'three' if adding one stone turns it into an open four — a four with empty points at both ends. If one side of the line already has a stone further out, so that extending it could only ever reach six or more (an overline), that side isn't a real three, even though the shape looks the same on the board.

That exception is why a shape that looks like a double three can sometimes still be played. The judgement is automatic here, so if there is no × mark, you don't need to recount the shape yourself.

Knowing which lines are genuine threes and which only look that way also helps with setting up the kind of trap covered in a later lesson, where your opponent's own shape works against them.

Chasing black into a forbidden move

Lesson 3

'Chasing into a forbidden move' is a tactic unique to renju, where white turns black's own restriction into a weapon. If white makes a four (one stone short of five) whose only blocking point also happens to be forbidden for black — a double three, double four or overline — then black loses either way: playing the point loses instantly, and not playing it lets white complete five next.

In this position, white already has four stones in a row with one end blocked by a black stone, leaving only one point that could stop it. That same point also sits where two of black's own lines cross, making it a double three for black. Avoiding it doesn't help, either — white simply plays it and completes five.

To set this up as white, look for a point where black's own lines already cross into a forbidden shape, then build your four so that point is the only way to block it. As black, keep an eye on where your own lines might someday create a forbidden point if one side gets blocked.

Win with a four and a three

Lesson 4

A four-three is one of the most common winning shapes, in renju just as in gomoku. One move that makes a four (one stone short of five) and an open three (three in a row with both ends free) at the same time forces your opponent to block the four — and while they do, extending the three creates two ways to make five, which can't both be stopped. A four-three combines one four with one three, so it is never a forbidden double three or double four, for either colour.

In this position, one side of black's row is already blocked by a white stone. Playing the glowing point turns the row into a four (open on the other side) while a diagonal line of black stones becomes an open three at the same time. White has no choice but to block the four.

To find a four-three, look for a point where two of your own lines cross. Even if the four side only has one open end, a genuinely open three on the other line is enough to decide the game on the next move.

The idea behind opening rules

Lesson 5

Because black always starts on the centre point, renju would strongly favour black with no further rule. Opening rules fix how the first few moves are decided. Under the default, Taraguchi-10, players alternate deciding who plays the next move — themselves or their opponent — while the area they may play in grows step by step, from a 3×3 square around the centre to 5×5, then 7×7.

Whichever opening rule is used, black's first stone always goes on the centre point, so no advantage comes from choosing where to start. Soosõrv-8, the pro rule (26 openings), and unrestricted free play are also available, but Taraguchi-10 is the one rule shared by both international tournaments and the Japanese Renju Association's own events.

For now, it's enough to remember that black's first move is always the centre, and that the first few moves are limited to a set area — the back-and-forth over who decides can wait until later.

Try it on the board

Pick a lesson and the board starts from that position. Start over as often as you like.

Now put it to work

Play with friendsLearn how to play (3 min)

Last updated 2026-09-23 · Run by Qdan, Inc.