How to win at Capture Go

Capture Go is a fight over liberties (the empty neighbors of a group of stones). The side that adds to its own liberties and cuts the opponent's wins.

Add liberties

A single stone has four liberties in the middle and two in a corner, and stones that are joined share their liberties. A group with only one liberty left (atari) is captured on the next move. So keep your groups from losing liberties, and when a group is in danger, connect it to gain liberties.

Drive the opponent into atari

Block the liberties of an enemy group one by one until it is down to one liberty (atari), and on the next move you can block that last liberty and capture. A small group pushed into a corner or against the edge has fewer liberties than a big connected group, so it is easier to capture.

Avoid self-capture

A move that fills the last liberty of your own group (self-capture) is not allowed, unless that move captures the opponent. Count liberties so you do not waste a move on self-capture when you play carelessly in a tight spot.

Greed loses

If you chase only your own liberties and ignore the opponent's next move, the opponent surrounds and captures your group. We measured this in our own simulation. We matched a side that ignores the opponent's reply against a side that looks one move ahead, and the side that did not look lost. Before you place a stone, check once more whether the opponent can put you into atari from that spot.

How to choose the day's rule

Three of the 4 candidate rules are drawn for the day. You ban one and pick one, and each rule works differently.

Think about what to ban first. Banning the one that hurts you most of the three is worth the most. For example, Two-stone capture blocks a plan of winning with a single capture, so if you were aiming for a quick capture, ban it first.

This is Capture Go, not full Go

This is not full Go, which counts territory. It is Capture Go, where the first to capture an enemy stone wins. That keeps a game short and the result clear. We say so plainly. The form is a shared pastime that belongs to nobody, and only the day's rule laid on top is ours.

How big is the board and when does a game end

The board has nine lines by nine (9x9), and stones go on the points where lines meet. You play black and move first, and the opponent answers with white. The first to capture an enemy stone wins on the spot. The exception is when the day's rule is “Two-stone capture”: then you must capture two or more stones with one move to win, and capturing a single stone does not count. No territory is counted, so there is no scoring and no komi, and a game usually ends in a few minutes.

What happens with ko (recapturing)

Full Go has a ko rule that stops you from recapturing right away so the same position does not repeat, but this app does not have that ban. In Capture Go the first to capture wins on the spot, so the game usually ends before it is your turn to recapture. We write this openly. If you want the full rules as they are, look for a place that plays territory Go rather than this app.