Go Tips

Four questions before you play

1. Does either side have a group with one liberty? If so, count that group first. Atari is more urgent than taking a large empty area.
2. After this stone, are my groups thicker, or thinner? A move that joins two weak groups is usually more reliable than grabbing an isolated point.
3. If the opponent ignores this, what is my next move? An answer means the move has a follow-up. No answer means you still need a clearer target.
4. Am I gaining something, or only chasing a stone that runs? Look around before you chase. The chase is worth it when the escape leaves you a larger territory. Stop when it only drags your stones into a long, thin string.

Count liberties before you attack: atari is not a capture

Atari only means the group has one liberty. It does not mean you must capture now, or save the stone now. Liberties are the empty points above, below, left, and right of the whole group. A diagonal stone does not join the group and does not add a liberty. If you have two liberties and the opponent has one, they can still run. Look at the side they escape toward, and whether your own stones get cut.

When the stones touch, don’t play yet. Count the empty points up, down, left, and right, then look for a diagonal stone you thought was already connected. It is not. To connect, play on the shared orthogonal point, the circles in the diagram. A play on another diagonal still leaves two groups.

Life needs two real eyes. Learn the false one first

First see whether the empty points join into one space. Two points that touch up, down, left, or right, with none of your stones between them, are one eye. A group with only that eye cannot live once its outside liberties are filled. Two empty points with one of your stones between them are ready to be tested one by one.

For each separated point, ask whether the stones around it are one group. A gap in the wall lets the opponent play in and the empty point disappears: that is a false eye. When the wall is one group and still has another liberty, filling the eye is suicide, so the opponent cannot play there: that is a real eye. With two real eyes, filling either one still leaves the other liberty, so that play is suicide too, and the group cannot be captured even when surrounded. With only one real eye, once the outside liberties are gone the opponent fills the eye and takes the group.

A corner has only one diagonal. The eye counts when that diagonal and the two neighboring stones of your color are one group. In the corner diagram the diagonal is empty. After White plays there, both black stones have only the corner point left. Black cannot fill that corner: the move is suicide. If Black plays elsewhere, White fills the corner and captures both stones. On the side and in the center, ask the same question: is the wall one group? Two opposite diagonals occupied by the opponent cut the wall, and the eye is false. Two adjacent diagonals occupied by the opponent often leave the wall connected. Check the cut before you count how many diagonals are taken.

If both eyes pass that test and one of them is a ko, the group is not settled. After the opponent takes the ko, positional superko on this board forbids an immediate return to the same position. Play somewhere else, wait for the answer, then come back to the eye.

When a group is surrounded, sort the empty points into one space or points already separated. Test each separated point for a false eye. If only one real eye remains, see whether an escape can join nearby stones on an orthogonal point.

Start from a corner. A proverb is not an order

A corner is a reasonable first look. Two edges are already closed, so the same few stones make an eye and territory more easily than they would in the center. That is not an order to occupy a corner on move one. A group with one liberty is more urgent than an empty corner.

On 9×9 the four corners are close. Take one, then see which side the opponent approaches from. You do not need all four at the start. Before you take a second, use the shapes above: are your stones only touching on a diagonal, and is the diagonal of that corner point still empty?

Take something from one AI game on this site

Open a 9×9 game on Gentle in the sidebar. Check only two things: whether you treated diagonal stones as one group, and whether a surrounded space is two real eyes, one false eye, or a single empty area.

• The hint uses the current level. On Gentle, the hint is Gentle’s search. It does not switch to another level. Point at the connection or the eye yourself, then look at the hint. A different point means this level sees a different urgent place.
• Online rooms cannot undo. Once the room accepts a move, it is sent to the opponent, so check again before you play. On a shared screen you can stop and count liberties together.

When to leave 9×9 for 13×13 and 19×19

Move to 13×13 when you can count the liberties of two diagonal stones separately, and can say whether an empty point is a real eye, a false eye, or one space. 13×13 uses the same rules. What changes is that the side and the center both need attention. 19×19 is not a different ruleset. You simply watch more groups at once.

Don’t use the result of the game to decide. If diagonals and orthogonal connections are still mixed up, or a false eye is still hard to spot, stay on 9×9.

Questions