The rules Suvi plays
Suvi plays freestyle gomoku on a 15×15 board. Five or more in an unbroken line wins, so an overline of six counts. There are no forbidden moves for either player and no special opening rule; the first stone can go anywhere. If all 225 points fill without a five, it is a draw, which almost never happens.
Freestyle favours the first player strongly: computer analysis has shown that on this board the first player can force a win with perfect play. People don't play perfectly, but take turns to start. Suvi swaps the starter after each game unless you press Swap.
Know the shapes
| Shape | Name | What it means |
|---|---|---|
| · · X X X · · | Open three | One more stone makes an open four. Answer it now. |
| · X X · X · | Split three | Just as dangerous; the gap is the key point. |
| O X X X · · | Closed three | Blocked at one end. Not urgent yet. |
| O X X X X · | Four | One point from five. Block it at once. |
| X X · X X | Split four | Also one point from five: the gap. |
| · X X X X · | Open four | Two winning points. The game is over. |
| X X · X X X | Four, freestyle | Filling the gap makes six, which still wins on Suvi. |
Learn to spot the split shapes. Beginners see three in a row at once but miss the same threat with a gap in it.
Tempo: why fours and threes force replies
A four must be blocked straight away, and an open three must be answered on the next move or it becomes an open four. Moves that demand a reply let you decide where the game goes; that is the initiative. A move that threatens nothing gives your opponent a free turn to build their own attack.
That is why a closed three is weak on its own: it threatens only a closed four, which one stone stops. Use closed threes as building material, not as attacks.
Building a double threat
A single threat can always be blocked. Games are won by making two with one stone:
- Four-three: a four and an open three on different lines. Your opponent must block the four, and the three becomes an open four.
- Double four: two fours at once. Only one can be blocked.
- Three-three: two open threes at once. Some rule sets ban this for the first player; Suvi's freestyle rules allow it for both of you.
| · | · | · | · | · | · |
| · | · | · | · | X | · |
| · | · | · | · | X | · |
| O | X | X | X | ★ | · |
| · | · | · | · | · | · |
| · | · | · | · | · | · |
O must block the end of the four on the right. X then plays just below ★ for an open four down the column, and wins.
To set these up, play where two of your part-built lines cross, not at the end of one long row. A stone that sits on two of your lines is worth far more than one that extends a single line. Then look for a chain of fours: make a four, they must block, make another with the next stone, and carry on until one four also makes a second threat. Every four forces a reply, so your opponent never gets time to defend.
Defending
- Block every four at once. There is no choice.
- Answer open threes now. There are usually two or three points that stop one; pick the one that also gets in the way of their other stones.
- Against a split three, block the gap. It breaks the shape in two. Blocking an end still lets them make a four and keep the initiative.
- Counter with a four. If you have a four available, you may play it first: they must block before carrying on. It only helps if your four leads somewhere or improves your defence.
- Take their crossing point. Find the empty point where two of their lines would meet. Taking it early stops a four-three before it exists.
Playing Suvi's computer
- Easy blocks your fours but often misses an open three. Make open threes and watch for the one it ignores.
- Medium blocks every open three and never misses a four-three of its own, but it doesn't look for long chains of fours, for itself or for you. A three-three, or a run of fours ending in a double threat, will often beat it.
- Hard always opens in the centre, searches chains of fours for both sides and defends against yours before they arrive. Go first, build quietly with stones that sit on several lines at once, and look for attacks that mix open threes with fours, which are harder for it to see coming.
Undo takes back your move and the reply; a hint shows the point Hard would choose.
If you only remember three things
- Fours and open threes must be answered; everything else can wait.
- Win with two threats from one stone, built where your lines cross.
- Block split threes in the gap, and take their crossing points early.
Try a four-three for yourself: play Gomoku against Medium. Fancy something smaller? Four in a Row uses many of the same ideas.
Questions
- Are double threes allowed in Suvi's gomoku?
- Yes. Suvi plays freestyle rules with no forbidden moves, so a three-three, a double four and an overline of six are all fine for both players.
- Is gomoku a win for the first player?
- In freestyle gomoku on a 15×15 board, yes, with perfect play. Between people the first player has a clear edge rather than a certain win, so swap who starts.
- What is the difference between a three and an open three?
- An open three has enough empty points at both ends to become an open four with one more stone. A three blocked at one end can only become a closed four, which is easy to stop.
- Where should I place my first stone?
- In the centre, the middle star point. Stones near the middle take part in the most lines. Going second, play right next to the first stone, either beside it or diagonally.
- How do I stop a split three?
- Usually by placing your stone in the gap. That splits it into a pair and a single stone. Blocking an end still lets your opponent fill the gap and make a four.
Play it now
Gomoku is free on Suvi, on your phone or computer, no download. Also: Gomoku vs Computer · 2 Player Gomoku · Gomoku With a Friend Online.