Rules

The board consists of 61 circular spaces arranged in a hexagon, five on a side. Each player has 14 marbles that rest in the spaces and are initially arranged as shown below, on the left image. The players take turns with the black marbles moving first. For each move, a player moves a straight line of one, two or three marbles of one color one space in one of six directions. The move can be either broadside / arrow-like (parallel to the line of marbles) or in-line / in a line (serial in respect to the line of marbles), as illustrated below.^[2]

Initial position

Black opens with a broadside move

White counters with an in-line move

A player can push their opponent's marbles (a "sumito") that are in a line to their own with an in-line move only. They can only push if the pushing line has more marbles than the pushed line (three can push one or two; two can push one). Marbles must be pushed to an empty space (i.e. not blocked by a marble) or off the board. The winner is the first player to push six of the opponent's marbles off of the edge of the board.^{[2] [3]}

Move notation

The notation for recording moves gives the letters A-I to the horizontal lines, and the numbers 1–9 to northwest–southeast diagonals.^[4]

     I O O O O O
    H O O O O O O
   G + + O O O + +
  F + + + + + + + +
 E + + + + + + + + +
  D + + + + + + + + 9
   C + + @ @ @ + + 8
    B @ @ @ @ @ @ 7
     A @ @ @ @ @ 6
        1 2 3 4 5

One popular notation: an inline move can be denoted by the movement of the trailing marble (the "caboose"); broadside moves can be denoted by the initial positions of the two extremities of the lance followed by the final position of the first marble (with this notation, each broadside move has two notations possible, which could be avoided).

Avoiding draws

The dynamics of the basic game may have one serious flaw: it seems that a good but conservative player can set up their marbles in a defensive wedge and ward off all attacks indefinitely. An attacker may try to outflank this wedge or lure it into traps, but such advances are often more dangerous to the attacker than the defender. Thus, from the starting position, it takes little skill and no imagination to avoid losing, and nothing in the rules prevents games from being interminable.

Because it is boring for games to be drawn out indefinitely, serious Abalone players tacitly agree to play aggressively. A player who forms a defensive wedge and makes no attempt to attack is likely to be a novice who might lose anyway. Nevertheless, there remains the possibility of any competent player bringing the game to a standstill and successfully avoiding losing, even to a championship-level player.

There are several possible "solutions". First, in tournaments, a judge may penalize a player for playing defensively. This solution is somewhat unsatisfactory, given that a judge may not always be present, and that "defensive play" is subjective.

Second, several variations of the rules have been developed for the same board and marbles. None of the variations has the same appealing simplicity of the original.

The third, and perhaps best, alternative starting positions have been designed to make the formation of stalemate wedges less likely. Experiments are still underway to find an opening position which neither devolves to a draw nor gives too great an advantage to the first player. One popular attempt are the Marguerite or Daisy positions, two versions of which are displayed in the center and to the right.

Another option is to create a "turn limit" where if no marble has been knocked off the board by turn 15, whoever has made the most progress towards the center line wins. This encourages an aggressive strategy of moving forward and often the rule will not come into play.

Black can defend forever

German daisy starting position

Belgian daisy starting position

Rule variations and more players

Abalone can be played by three or more people using the same board with fewer marbles for each player and each player has a different colour.^[5][6]

A number of two-player variations use a third colour for passive pieces. For example, the variation called The Pillar (with a fixed marble in the centre of the board), which has been examined to some depth by Alex Borello and Nicolas Le Gal, uses a third colour. Another possible variation involves either player winning the game by ejecting the central marble.

A few variations use a second layer of marbles.