Gomoku vs Renju: What's the Difference?

If you've spent any time reading about Gomoku online, you've probably run into the word "Renju" and wondered: aren't they the same thing? They're both played on a 15×15 grid, both use black and white stones, and both are about getting five in a row. So what gives?

The short answer: Renju is a tournament variant of Gomoku with extra rules to fix a fundamental problem — in standard Gomoku, the player who goes first (Black) has a massive advantage. Renju patches that with specific restrictions on how Black can play.

Here's the full breakdown of what changes, why it matters, and which game you should actually be playing.

The core problem: first-player advantage

In standard Gomoku (free-style, no restrictions), the player who goes first — Black — wins way more often than they should. The exact win rate depends on the skill level, but at high levels Black wins something like 70-80% of games when both players know what they're doing.

That's not great for a competitive game. Imagine playing chess if White could force a win 75% of the time. Not much of a contest.

Renju was developed in Japan in the early 20th century specifically to solve this problem. The solution: add rules that restrict what Black can do, while leaving White unrestricted.

What Renju changes

Renju keeps the same board and the same goal (five in a row wins). But it adds three key restrictions on Black:

1. Forbidden moves for Black: Black is not allowed to play a "double three" (two separate live threes in one move), a "double four" (two separate live fours), or "overline" (six or more in a row). White has no such restrictions — if White gets six in a row, they win.
2. Opening rules: The first three moves are played according to a specific sequence (the "opening rule"), often with White choosing where Black's second stone goes. This prevents Black from picking the most aggressive possible opening every time.
3. Swap rule (in modern variants): Some Renju competitions use a "swap" rule where players can exchange colors after the opening phase, further reducing the first-player advantage.

These restrictions dramatically balance the game. In tournament Renju, the win rates between Black and White are much closer to 50-50.

Which one should you play?

Play standard Gomoku if: You're playing casually with friends, you want a simpler rule set, or you're just learning the game. The forbidden-move rules in Renju add a layer of complexity that can feel overwhelming when you're still getting comfortable with basic pattern recognition.

Play Renju if: You're getting serious about competition, you want a perfectly balanced game, or you find that going first in Gomoku feels like an automatic win. Renju is also the version played in official world championships, so if you have competitive ambitions, this is the version to learn.

Can you play Renju on trygomoku.com?

Right now, our online game uses standard Gomoku rules (free-style, no forbidden moves). We're considering adding a Renju mode based on player interest — if that's something you'd use, let us know. In the meantime, the AI difficulty levels are calibrated for standard Gomoku and provide a fair challenge at every skill level.

The forbidden-move rules of Renju also make for interesting strategic wrinkles. For example, as Black, you have to be careful about building a double-three — it might look like a winning position, but if you accidentally create one, you lose the game instantly. That creates tense moments where your opponent is trying to force you into a forbidden move, and you're trying to avoid it while still building your attack.

Worth trying both and seeing which clicks with you. A lot of players actually prefer standard Gomoku for casual play (less to remember) and Renju for serious competition (fairer for both sides).