Arimaa
Overview
Arimaa is a two-player abstract board game invented by Omar and Aamir Syed in 2002.

Board

Arimaa is played on a 8x8 board.  There are four special cells called "traps", which are intended for capturing pieces:

 

Pieces

There are two players in the game: Gold and Silver.

Each player has 1 elephant, 1 camel, 2 horses, 2 dogs, 2 cats and 8 rabbits:

Gold Elephant   Silver Elephant
Gold Camel   Silver Camel
Gold Horse   Silver Horse
Gold Dog   Silver Dog
Gold Cat   Silver Cat
Gold Rabbit   Silver Rabbit

 

Objective

A player wins the game if one of his own rabbits reaches the opposite line of the board.

Play

The game starts with an empty board.

During the first phase of the game both players place their pieces on the first two rows of the board. The player with the gold pieces sets them first and then the second player sets his pieces on his side of the board. The players can set their pieces on the first two rows in any arrangement. There is no fixed starting position.  Below is an example of a typical position:

After the first phase the actual play begins. The players take turns moving their pieces with the gold player going first.

Each move consists of one to four steps. Each step is a movement of a piece to a horizontally or vertically adjacent empty cell. All pieces can move forward, backward, left and right with each step, except the rabbits cannot move backward. They can only move forward, left and right.

A piece can change directions after each step and several pieces can be moved during a turn:

 
Gold makes a move consisting of 4 steps.  All steps are made using a gold horse.   Gold makes a move consisting of 3 steps: 2 steps are made using a gold horse and a one step is made using a gold dog.

Stronger pieces can move the opponent's weaker pieces.  For example a gold dog can move a silver cat or silver rabbit, but not a silver dog, horse, camel or elephant. An opponent's piece can be moved by either pushing or pulling it.

To push an adjacent opponent's piece with your stronger piece, first move the opponent's piece to one of the adjacent cells and then move your piece to the cell where the opponent's piece was "pushed" from:

 
Gold moves a silver dog to an adjacent empty cell.   Gold completes the "push" by moving the gold horse to the cell where the silver dog was "pushed" from.

To pull an adjacent opponent's piece with your stronger piece, first move your piece to one of the unoccupied adjacent cells and then move the opponent's piece into the cell where you moved your piece from:

 
Gold moves his gold horse to an adjacent empty cell.   Gold completes the "pull" by moving the silver dog to the cell where the gold horse was moved from.

Moving an opponent's piece is counted as a step.  Thus "pushing" or "pulling" requires two steps.  The "pushing" or "pulling" must be completed within the same turn. It is forbidden to start a "push" or "pull" in one turn and complete it in another turn. Any combination of "pushing" and "pulling" can be done in the same turn.  However, when your stronger piece is completing a "push" it cannot "pull" an opponent's weaker piece along with it.

 

Stronger pieces may freeze weaker enemy pieces if they are alone. If a piece is adjacent to a stronger opponent's piece and there are no friendly pieces (either weaker or stronger) adjacent to it then the piece is considered to be frozen and cannot be moved by its owner. However, such a frozen piece can be "pushed" or "pulled" by an opponent. Below are several examples:

 
A gold cat is frozen because it is adjacent to the stronger opponent piece (silver elephant) and there are no friendly gold pieces adjacent to the gold cat.   A gold cat is not frozen in spite of being adjacent to the silver elephant because there is a friendly piece (gold dog) adjacent to the gold cat.

There are four special cells called "traps" (c3, f3, c6 and f6).  Any piece that is standing on a "trap" is immediately removed from the game if there are no friendly pieces adjacent to it.  A piece can step into a trap by itself and be removed from play.  But usually pieces are "pushed" into traps by stronger opponent's pieces. Below are several examples:

Pushing an opponent's piece into the trap
   
The gold horse pushes the silver dog into a trap.   The are no friendly silver pieces adjacent to the "trapped" dog.  Therefore the silver dog is removed from the game.   Gold completes the "push" by moving the gold horse.

 

Pushing an opponent's piece into a trap when there is another opponent piece next to it
   
The gold horse pushes the silver dog into a trap.   There is a friendly silver cat adjacent to the "trapped" dog. Therefore the silver dog is not removed from the game.   Gold completes the "push" by moving the gold horse.

 

Pushing an opponent's piece that secured a "trapped" opponent's piece
   
The gold horse pushes the silver cat.   The silver dog does not have any friendly pieces adjacent to it.  Thus it is removed from the board.   Gold completes the "push" by moving the gold horse.

Special Situations

A player may push or pull the opponent's rabbit into the goal. If at the end of a turn the opponent's rabbit remains there, the player loses.   However, if the rabbit is moved back out of the goal row before the end of the turn, the player does not lose.

A player wins the game if his opponent remains without rabbits. If both players are left without rabbits on the same turn then the player making the move wins.

A player wins the game if he leaves his opponent without legal moves, i.e. either all opponent pieces are "frozen" or have no space to move.

If after a turn the same board position and side to move would be repeated three times, then that move is considered to be illegal and the player must select a different move. If in the rare case the only moves a player has are not allowed then the player loses due to being unable to make a move.

License Notes
Arimaa is a proprietary game which is patented and trademarked. It is being provided on igGameCenter with written permission from Arimaa.com and in compliance with "Section 2 of the Arimaa Commercial License" which can be found at www.arimaa.com.

External Links