Gomoku Beginner Tips: Line Up Five Before the Computer Blocks You (2026)

Last updated: September 27, 2026 · Tested on Playnesta's Gomoku build (upstream TranHuuDat2004/Caro-Board @ 31ec6d3) · Goal: line up five stones before your opponent

Method: every rule below was verified against this site's playable build — constants read from the shipped game (20x20 grid with 400 intersections, five in a row wins across four directions, three menu modes: Player vs Player plus Player vs Computer as X or O, X always moves first, defense-first computer that blocks instant losses first, takes instant wins second, and blocks open threes third, winning five highlighted cyan, full board with no five scored a draw, in-page Play Again for an instant fresh board), a headless-browser check confirmed a clean start with zero errors, a 400-cell board, a Player-vs-Player X five-in-a-row with all 5 cells highlighted, bridge load/start/win/restart events reaching the parent page, a Play Again press clearing board and results, the computer answering as O within a second, and zero errors at 390px mobile width with no sideways scroll. Controls: click or tap any empty intersection on desktop and touch; mode buttons and Play Again are 44px tap targets. Gomoku is a centuries-old public-domain board game, played here under its own name.

1. Open near the center — edges starve your lines

A center stone can grow lines in all four directions; a corner stone grows in only two. The shipped computer prefers playing next to existing stones, so a central opening drags its replies into the traffic jam you control instead of letting it develop freely on an empty wing. First stone within the middle 6x6, always — edge openings donate the initiative before move five.

2. Build open threes, not long single lines

This computer blocks your instant five every time and blocks open threes too — a lone four with one open end is already dead the moment you make it. The unit that matters is the open three (three stones with both ends free): it threatens to become an open four the computer must answer. Stack open threes and the computer spends every move defending while your position keeps growing.

3. Force double threats — one threat is a free block

Because the defense answers exactly one danger per move, two simultaneous threats win on the spot: whichever open four it blocks, the other completes five. The practical shape is a fork — one stone that creates open threes on two crossing lines at once. Stop extending a single line past three stones; instead ask every move "does this create two problems," and play the move that does.

4. As O, defend first — X moves first for a reason

X always moves first in this build, so playing as O means answering, not leading: meet every X three before building your own, and keep your stones touching X's stones to deny free space. The verified test win came as X in Player-vs-Player mode — if you keep losing as O against the computer, switch sides to X and feel how the first-move tempo turns the same ideas into wins.

5. Practice in Player-vs-Computer, settle it in Player-vs-Player

The computer never misses a block, which makes it a strict teacher but a misleading scoreboard — real opponents miss things. Drill ten games as X against the computer to internalize open threes and forks, then play a friend on the same screen where the same patterns land twice as often. When a game goes wrong, hit Play Again and replay the opening differently — the instant restart exists so one session holds five practice games, not one long regret.

FAQ

What is the goal of a game?

Line up five of your stones in a row — horizontal, vertical, or diagonal — before your opponent does. The winning five light up cyan and the page announces the winner.

What happens if the board fills up?

A full 20x20 board with no five in a row is a draw: the page shows "It's a Draw!" and Play Again deals a fresh board. (Draw scoring was verified from the shipped game code; a full 400-move draw was not live-played.)

How does the computer decide its moves?

Defense first: it blocks your immediate five, takes its own immediate five, blocks your open threes, then plays next to existing stones. It never sets traps — so every loss is a lesson in which threat you failed to double.

Can I play against a friend?

Yes — pick Player vs Player from the menu and alternate X and O on the same screen. No account, no second device, and Play Again restarts instantly.

Does it work on mobile?

Yes — stones are placed by tap on the same intersections as desktop clicks, mode buttons and Play Again are 44px targets, and the board shrinks to fit 390px viewports with no sideways scroll.

Where can I play it?

Right on this site's gomoku page. The game is a self-hosted modification of the MIT-licensed Caro-Board by Tran Huu Dat; license and attribution are listed under the game.