A Brief Introduction to the Ancient and Honourable Game of Go.

(The original version was written by Charles Roth, circa 1991, in his SCA identity of "Captain William Brigandyne".  The original was scanned and migrated to the web in 2016.)

INTRODUCTION
The game of Go has been played in its current form for at least 1000 years, principally in China and Japan.  While the rules of Go are very simple, the game has tremendous depth, and can be enjoyed by players of all skill levels.  The philosophy of the game is very different from Western games such as Chess.  Rather than focussing one's energies on a specific goal and smashing through to victory, the Go player learns to weave a fragile net around the opponent, slowly tightening the noose.

EQUIPMENT
Go is usually played on a board covered by a 19 by 19 grid of lines.  Players place black and white pieces, called stones, on the intersections of the lines, called points.  The truly proper board is mounted on four wooden legs, about 8 inches high.  Underneath the board is placed an empty bowl -- purportedly to catch the blood of kibitzers.  Games may also be played on smaller boards, typically 9 by 9, or 13 by 13.  Using a small board is an excellent way to learn Go, or to play a game when time is limited. 

GOAL
The goal in playing Go is to surround as much territory as possible with your stones.  Each open point that you surround is worth a value of 1.  You may also capture your opponent's stones; each stone that you capture subtracts 1 from your opponent's score. 

MOVEMENT

  1. Players alternate placing a stone on any unoccupied point.  Black moves first. 
  2. A player may pass a turn (choose to not play a stone) at any time.  Passing once does not mean you pass forever; you may choose to play a stone on your next turn. 
  3. The game is over when both players pass in succession. 

LIBERTIES and CAPTURE
In most cases, you may place a stone on any open point.  The exceptions have to do with capturing, and the concept of "liberties". 

  1. Consider a single white stone on an empty board.  It has four liberties -- the adjacent open points above, below, to the left, and to the right.  Points on the diagonal have no effect. 
  2.     
    Figure 1 Figure 2
    The same white stone in Figure 1 has three liberties; the black stone has taken away one of its original liberties.  In figure 2 the white stone has just one liberty, point A.  If Black places a stone there, the white stone has no liberties, and it is immediately removed.  Black keeps the captured White stone, to subtract from White's score at the end of the game. 
  3. Note that a stone on the edge of the board has only three liberties to start with.  A stone at one of the four corners of the board has only 2 liberties to start with.  This has important strategic consequences. 
  4. It is traditional to warn the other player when you threaten to capture a stone.  In figure 2, when Black plays the stone marked B, Black says "Atari".  This warns White that one or more of White's stones has only one liberty left. 
      
    Figure 3
  5. Everything that is true about a single stone also holds for a group of connected stones.  Stones of the same color are connected if they are immediately adjacent to each other, horizontally or vertically.  Once again, diagonals do not count.  Connected stones "share" their liberties.  For example, the White stones in figure 3 form one connected group that has two liberties.  Should Black place stones at A and B, the entire White group will be captured.  (Note that Black's stones are not all connected.)
  6.   
    Figure 4
    A stone may not be placed in a position where it has no liberties, since it is effectively captured immediately.  To quote Fairbairn, "...despite the Oriental predeliction for suicide, it is not permitted in Go."  Thus, White may not play at point A in figure 4. 
  7.   
    Figure 5
    A stone may be placed in a position that apparently has no liberties, if in doing so it captures another stone and opens up a liberty.  Consider figure 5.  White can place a stone at A, because it captures the Black stone at B, and opens up a liberty. 
  8.   
    Figure 6
    Rule 7 can lead to an "infinite loop".  Figure 5 becomes figure 6 when White places a stone at A.  Black might then play back at B, capturing the White stone at A, and returning the board to figure 5.  This kind of boredom is prohibited by the "rule of Ko", which states that no stone may be played which would recreate any earlier entire board position.  Thus in figure 6, Black cannot play at B, but must place a stone somewhere else.  After that, however, the board position has changed, and Black can play at B -- assuming White did not play there in the interim. 

SCORING

  1. When both players have passed, the game is over and scoring begins.  Both players must agree on which stones are "dead" and which are "alive".  Dead stones would have been captured if play continued long enough.  If the players do not agree, then play should continue.  This sounds like a source of possible argument, but after a few games it will become obvious to both players. 
  2. Remove all dead stones as though they had been captured. 
  3. Look for empty points that are adjacent to both black and white stones.  These are called "dame", and count for neither side.  Fill in the dame with stones of either color -- traditionally, black and white alternate.  (It doesn't really matter, as it won't affect the scoring.)
  4. Place the stones that you captured into your opponent's territory.  This essentially subtracts the captured stones from your opponent's score. 
  5. Within the boundaries of your territory, rearrange the stones to make the territory easier to count (or more aesthetic, if you like).  Count up your territories, and compare.  Largest number wins! (Just count the empty points in your territory -- not the stones that surround them.)

TACTICS

  
Figure 7
The single most important tactical concept is the double-eye structure.  A structure is a single group of connected stones.  An "eye" is a hole in a group of connected stones.  Figure 7 shows a common one-eye structure.  A one-eye structure is difficult to capture: you must first surround it to take away the outer liberties, and then (and only then) place a stone in the hole to take away the inner liberty, capturing the entire group.  (Trying to place a stone in the hole before then is suicide and therefore illegal.)

  
Figure 8
Figure 8 shows other forms of the one-eye structure that can be made near the edge of the board. 

  
Figure 9
Figure 9 shows a two-eye structure.  It is invulnerable, and can never be captured.  (To do so, you would first have to surround the outside, and then place a stone in both holes simultaneously!  But since you can only place one stone at a time, and placing a stone in one of the holes is suicide, it follows that you can never capture the group.)  Figure 10 shows other forms of the two-eye structure. 

  
Figure 10
Every game of Go, without exception, revolves around building a two-eye structure -- or building a loose network of stones that you can turn into a two-eye structure when needed.  Not only is the two-eye structure safe, but so are all the rest of your stones that can be connected to it!

Because two-eye structures are more easily built near the corners and edges of the board, a typical Go game starts with both players placing stones near the corners, then near the edges, and then slowly working their way out into the center.  Learning the trade-offs between securing corners and edges versus laying claim to large amounts of territory is part of the fascination of Go. 

HANDICAPS
Go has a detailed ranking scheme that includes a handicap system.  The less skilled player always plays Black, and is given 2 to 9 stones.  They are placed in a standardized symmetric pattern on the handicap points marked with a small black dot.  White then makes the first move. 

This is sometimes disconcerting to Western players, who may want to "just get in there and fight it out."  In practice the use of handicap stones makes the game more enjoyable for both players.  The best strategy for a Black player with handicap stones is to "give up" half of the corners implied by the handicap stones, and concentrate on reinforcing the other corners immediately. 

BIBLIOGRAPHY
This document is intentionally very brief, and only touches on tactical and strategic concepts.  Unfortunately, most books on Go are uniformly terrible, so I strongly recommend one of the books below: