A complete guide: the goal, placing stones, liberties and capturing groups, the ko rule, counting territory, controls on muta.pro and tactics for beginners.
Go is a duel between two players, Black and White. Your task is to control more territory than your opponent: fence off empty intersections with your stones and, along the way, capture as many of his stones as you can. Nothing is decided "in one blow" — the score is made up of the surrounded area and the prisoners, and at the end the final totals are compared.
The game is played on a grid of lines — on muta.pro this is a 13×13 board with marked reference points. Stones are placed not in the squares but on the intersections of the lines. The board starts empty; Black moves first, then the players alternate. A placed stone does not move until the end of the game — it can only be lost by being surrounded.
On your turn, place one stone of your color on any empty intersection. Passing is also allowed if placing a stone would not help you.
A liberty is an empty intersection adjacent to a stone along a line. A stone or a connected group stays alive as long as it has at least one liberty.
If your move takes away the opponent group's last liberty, the whole group is removed from the board and taken as prisoners.
You may not place a stone so that it is immediately left with no liberties — unless that very move captures an opposing group.
You may not immediately repeat the position that existed one move ago. First play elsewhere, and only then may you return to the contested point.
When both players pass in a row, the game ends and counting of territory and prisoners begins.
Victory is decided on points. For each player you count the surrounded territory — empty intersections fenced off by their stones alone — plus the prisoners taken. Whoever's total is larger wins. On muta.pro the "Captured ⚫" and "Captured ⚪" counters show the number of captured stones as the game goes, while the "Move N" indicator marks its length.
Corners and sides are easier to fence off than the center: there a stone needs fewer liberties to live.
A group with two separate empty "eyes" is invulnerable — it can never be captured.
It is better to hold a middling area firmly than to reach for the whole board and lose your weak groups.
Before every move, count whose group has fewer liberties — that tells you whom to attack.
The whole mechanic of Go rests on one idea — the liberty (in Japanese, "dame"). It is an empty intersection adjoining a stone along a straight line — up, down, left or right (diagonals do not count). A stone or a connected chain of stones stays alive as long as it has at least one liberty; the move that takes away the last one removes the whole group from the board and takes it prisoner. That is why Go is not "who eats a piece" but who suffocates a group faster, by counting the free points around it.
The white stone in the center has one liberty left below — Black plays there and captures it.
Before a contact skirmish, count the outside liberties of both groups. Whoever is ahead by even one wins the capturing race — don't start a fight in which you are behind by a tempo.
Adjacent stones of the same color form a group with a shared set of liberties. By joining two of your stones you don't just add material — you pool their dame, and such a group is harder to suffocate.
You may not place a stone on a point with no liberties — except when the same move removes an opposing group and frees up a liberty for you. That is the only exception to the rule.
The main law of Go is simple: a group with two separate eyes can never be captured. An eye is an empty intersection completely surrounded by your own stones. The opponent may not play into it: his stone would be left without a liberty and would be removed at once. If there is only one eye, the opponent packs the group from the outside and at the decisive moment plays inside — that same move also takes the last liberty. But it is impossible to occupy two eyes in one move, and one at a time they can't be touched. Hence — immortality.
Two separate empty eyes inside the black wall — the group lives forever and cannot be killed.
Give a group two eyes before the opponent surrounds it from the outside. A big, handsome group with no eyes isn't territory — it's future prisoners.
An eye whose corner stone can be captured is not an eye. As soon as that stone is taken, the "eye" falls apart. Check the strength of the stones that form the walls.
In the corner, two eyes need fewer stones than on the side, and far fewer than in the center. Building a base for life is most economical right at the edge.
Atari is check: the opponent's group has a single liberty left, and the next move will remove it. But don't declare atari too early — first look at where the stone would run. If it is doomed, the ladder (shicho) works: you drive the fugitive in a zigzag, leaving it exactly one liberty at each step, and it rolls toward the edge of the board, where it dies entirely. The danger is that the whole path of the ladder must be read in advance: a single stone friendly to the opponent on the trajectory (a "ladder-breaker") breaks the ladder — the fugitive gains a second liberty, and now your pursuers fall into atari.
The ladder: the white stone is trapped, and each Black move (✕) drives it in a zigzag toward the edge to its death.
When the ladder does not work because of a ladder-breaker, you catch the stone with a net (geta): instead of chasing right up against it, you place a stone slightly at a distance, sealing off every escape route. The net is more reliable than the ladder because it does not depend on other stones on the board, though it usually leaves the opponent a stone or two fewer prisoners.
The net (geta): the black stone at a distance (highlighted) covers the white one, wherever it may dash.
Sometimes the two sides could endlessly capture the same stone back and forth, returning the board to its previous position. The ko rule forbids this: you may not, with a move, repeat the position that existed one move ago. First play a ko threat elsewhere — a move the opponent cannot afford to ignore — and only when he answers it may you return to the contested point. Ko turns a small skirmish into a bargaining of threats across the whole board: the winner is the one with the richer stock of big threats.
The contested ko point (highlighted): you can't take the stone back at once — first you need a threat elsewhere.
The game ends when both players pass in a row with the "Pass" button. Then counting begins: for each player you add up the surrounded territory (empty points fenced off by their stones alone) and the number of prisoners. The larger sum wins; the "Captured ⚫/⚪" counters on muta.pro keep track as the game goes.
While contested borders (the "yose") remain on the board, one precise move along the edge in the endgame can easily be worth five or six points. Pass only when no big moves are left.
An extra stone inside finished territory occupies a point that would otherwise be your point — that's a pure minus. Worse, this way you can accidentally reduce two eyes to one.
Before getting into a ko, weigh who has more big threats in reserve. Whoever is poorer in threats loses the fight for the contested point, however important it may be.