Before every game on the home board you pick one of two rule sets: freestyle or blocked ends. They share almost everything — the same 15×15 board, the same alternating turns, the same goal of five in a row — and differ in exactly one detail. But that single detail changes the character of the game more than you might expect. This article puts them side by side so you can choose deliberately.
The single difference
Freestyle: five or more of your marks in an unbroken line wins, no matter what surrounds it.
Blocked ends (Vietnamese caro): a line of five wins only if it is not blocked by opponent marks at both ends. If the points directly beyond each end of your five are both occupied by the opponent, the five is dead and the game continues.
Everything else is the same. We cover the blocked-ends rule itself in detail in the blocked-ends rule; here we compare how the two versions play.
How freestyle plays
Freestyle is gomoku at its purest. Every line you build is a potential winner, so the game rewards accumulation: marks placed near other marks, lines in several directions, a growing cluster that eventually produces more threats than the opponent can block.
Because any five wins, the defender's job is purely reactive. You block the most dangerous threat, then the next, then the next. You cannot permanently kill a line with a clever block — you can only stop it from reaching five for now. Over a long game this favours the side with more marks in useful places, which is usually the first player.
Freestyle is therefore:
- easier to learn, because there is nothing to remember about ends,
- sharper for the first player, whose extra move counts for more,
- faster, because attacks convert into wins with fewer preconditions.
How blocked ends plays
Blocked ends adds a defensive resource: the double block. If you place marks on both ends of an enemy line, that line can never win again, however long it grows. Suddenly defence is not only about the current threat; it is about which lines you have half-killed and which you can finish off.
That changes attack too. An attacker in blocked-ends caro:
- values open space far more, because a line growing toward an enemy mark is already half dead,
- avoids cashing in one-sided fours, since forcing a block on the only open end kills the line,
- relies on double threats — two separate threats created by one move — because single threats can be neutralised for good.
Games tend to be a little longer and more tactical. The first player's advantage shrinks, though it does not disappear.
A position that plays differently
Imagine X has a four on a row, blocked at one end by O, with the other end empty.
In freestyle, O blocks at k8 and row 8 is finished for now — but if X ever manages to extend the line elsewhere into six or more, it could still matter. In practice this is rare.
In blocked ends, the moment O plays k8 this stretch of row 8 is dead forever: the four X marks sit between O's f8 and k8, so they can never become part of a winning five. For the defender this is a clean result. For the attacker it means the four was a one-shot forcing move. An experienced blocked-ends player therefore asks, before pushing to a four: is the forced reply going to help me elsewhere? If not, they keep the three and wait.
Which should you play first?
Start with freestyle for your first handful of games. It lets you focus on the core skill — seeing threats in all four directions — without an extra rule to track.
Move to blocked ends once you win the occasional game against the easiest computer level. You will notice two things quickly. First, some of your usual wins stop working because the computer kills your lines with double blocks. Second, you start defending better, because you learn to count ends. Both are good for your game.
If you plan to play with Vietnamese friends — in a café, at school, in the office — blocked ends is what they will expect. Many Vietnamese players have never played freestyle at all.
Do the same principles apply?
Almost all of them. The fundamentals of threats — open threes, fours, double threats, keeping the initiative — work in both versions. What changes is how much each threat is worth:
| Pattern | Freestyle | Blocked ends |
|---|---|---|
| Open four (both ends empty) | Wins | Wins |
| Four blocked at one end | Forces one reply | Forces one reply, and that reply kills the line |
| Open three | Must usually be answered | Must usually be answered |
| Three blocked at one end | Minor threat | Very minor threat |
| Line touching enemy marks at both ends | Can still win if it reaches five | Dead |
The table shows why blocked-ends players are so careful with the direction of their lines: any line already touching one enemy mark is one mark away from being worthless.
How to practise the switch
Changing rule sets is a bit like changing the size of the board: your instincts need a few games to recalibrate. A simple plan works well.
Week one: freestyle only. Play the computer on its easiest level until you win about half your games. Focus on one habit: after every opponent move, look along all four lines through that mark. Freestyle is forgiving enough that this single habit carries you a long way.
Week two: alternate. Play one freestyle game, then one blocked-ends game, against the same level. After each blocked-ends game, use the undo button to step back to the moment one of your lines died and ask whether you could have grown it in the other direction.
Week three: blocked ends only. Now you are learning to defend with double blocks and to attack with double threats. Raise the computer's level when you start winning comfortably.
Players who follow a rhythm like this usually find that blocked-ends play improves their freestyle game too. Counting ends makes you a more accurate reader of every threat, and the discipline of not wasting forcing moves carries over directly.
Etiquette when rules differ
If you sit down with someone new, it is worth saying the rule out loud before the first move. Disputes in casual caro almost always come from this: one player thinks a surrounded five wins, the other does not. A two-second agreement at the start saves a lot of arguing at the end — and it is exactly why this site asks you to choose the rule before the game rather than after.
Online games
When you play online against real people, make sure you know which rule the game uses before the first move — the same position can be winning under one rule and harmless under the other. If you invite a friend with a link, agree on the rule you both prefer.
Frequently asked questions
Is freestyle gomoku easier than caro?
The rule is simpler, so it is easier to learn. Playing well is hard in both.
Why do Vietnamese players use the blocked-ends rule?
It gives the defender a real technique and makes the game less one-sided in favour of the first player. It is also simply the rule generations of players learned at school.
Does the blocked-ends rule make games longer?
Usually a little, because the defender can permanently neutralise lines and the attacker needs cleaner double threats.
Can I practise both rule sets against the computer?
Yes. You choose the rule set before each game on the home board.
