Arimaa

The game begins by placing the pieces in any order on your own two base lines.

Arimaa is a strategic board game for 2 players developed by Omar Syed, an Indian-American computer scientist specializing in artificial intelligence . Syed was inspired by Garri Kasparov's defeat against the chess computer Deep Blue . So he wanted to develop a new game that is very difficult for computers to master, but should have rules that are simple enough for his four-year-old son Aamir to understand. The name Arimaa is an ananym from Aamir preceded by a.

In 2002, Syed published the Arimaa rulebook and announced prize money of $ 10,000 by 2020 for the first computer program that could beat a top human player in a tournament with six or more games. In the spring of 2004, David Fotland presented the strongest Arimaa program to date, which, however, was defeated 8-0 by Syed himself in a tournament. Until 2014, the strongest computer program was beaten by the people in the annually repeated competition. In 2015, however, David Wu's Sharp program finally won the Arimaa Challenge.

Syed has applied for a patent for the Arimaa rules and has the Arimaa name protected. The game has won several awards including "Best Abstract Strategy Game" from GAMES magazine 2011 and "Strategy Game of the Year" from Creative Child magazine 2010.

regulate

Game material

Arimaa is played on a normal size chessboard with four squares (c3, f3, c6, and f6) marked as "traps". The two players, gold and silver, each have 16 figures of six different types. In descending order of strength, these are: 1 elephant, 1 camel, 2 horses, 2 dogs, 2 cats and 8 rabbits. These pieces can also be represented by chess pieces ( king , queen , rooks , bishops , knights and pawns ), with white standing for gold and black for silver.

Game objective

The aim of the game is to move your own rabbit to the opposite side. The player wins gold if a golden rabbit is on the eighth row after a move (regardless of which party), and silver accordingly if one of his rabbits has reached the first row.

Game start

The game starts with an empty board. Gold places his 16 pieces in any order on the first two rows. Then Silver places his 16 pieces on the fields of the seventh and eighth rows, too. Then the players take turns taking turns, starting with gold.

Rules of move and course of the game

Each move consists of one to four steps . Each step moves its own pawn to an orthogonally adjacent field, i.e. to the right or left, forwards or backwards, not diagonally. The rabbits cannot be moved backwards, only sideways or forward. The steps of a move can either be carried out by the same piece or divided between several pieces. All four possible steps do not have to be followed.

At the end of a move, there must have been a change of position on the board, so you cannot move a piece one space back and forth, which would virtually suspend the move. In addition, after a move, a position cannot be created that has already occurred twice in the same game. This rule prevents endless loops, similar to the Super-Kō rule in the game of Go and differs from the game of chess , where repeating the position three times at the request of a player leads to a tie. Arimaa can never end in a draw.

The game does not end if a rabbit reaches the last row during a turn, but is no longer there at the end of the turn.

To evict

With a movement of a piece, the moving player can drive away an orthogonally adjacent weaker opponent's piece . For example, your own dog can drive away an opposing cat, but not a dog or horse. This can be done either by pulling or pushing . When moving, the stronger piece moves to an adjacent empty space and the space that it has made free is occupied by the piece you moved. So the silver elephant can move on d5 to d4 (or c5 or e5) and move the golden horse from d6 to d5. When you move, on the other hand, the opposing piece is pushed onto an adjacent empty space, after which your own piece occupies the space that has become free. The golden elephant on d3 can move the silver rabbit from d2 to e2 and occupy d2 itself.

Own figures cannot be distributed. In addition, a figure cannot move and push at the same time. If the golden elephant on d3 moves the silver rabbit from d2 to e2, it cannot move the silver rabbit from c3 to d3 at the same time. An elephant itself can never be driven away because there are no stronger figures. A rabbit can be pulled or pushed backwards even if it cannot move backwards by itself.

Driving away takes two steps of a turn. Moving your own piece counts as one step, driving away the opponent as another. Thus, you can only expel a piece a maximum of twice per turn.

Hold tight

A figure that is orthogonally next to a stronger opponent's figure is captured , unless it is also next to its own figure (whose strength does not matter). Held pieces cannot move, but they can hold onto other weaker pieces themselves and they can be driven away by the opponent. The silver rabbit on a7 is held, but the one on d2 can move as it borders on another silver piece. The golden rabbit on b7 is also recorded, but the golden cat on c1 is not. Again, an elephant cannot be held because it is the strongest figure. He can, however, be blocked by occupying all adjacent spaces and not being able to move a piece, either because it is his own or because it is not next to an empty space to which it could be moved.

In the position shown, gold could win in 3 steps: The dog on a6 can push the rabbit from a7 to a8. When the dog is then on a7, the rabbit is no longer held on b7 and can be moved to b8.

To catch

A piece entering a trap or being dragged or pushed into a trap is captured and removed from the game board, unless a piece from the same party is adjacent to the trap. When it is silver's turn, the golden horse from d6 can be captured by the elephant from d5 pushing it to c6. A piece on a trap is also captured if the last adjacent piece from the same party is moved (or driven away). So if the silver rabbit on c4 and the silver horse from c2 are moved, either voluntarily or by being driven away, the silver rabbit on c3 is trapped.

A figure can also be moved to a trap voluntarily, even if it is captured by it. The second step in pulling is then carried out, even if the pulling figure is captured by a trap in the first step. For example, Silver can move the rabbit from f4 to g4 and then move the horse from f2 to f3. Although it is captured by this, it can move the golden rabbit from f1 to f2.

After each movement of a piece, any trapped pieces are removed from the board, even if the move has not yet ended. So z. B. Silber move the horse to b2 and the rabbit from c4, and then move the golden dog with the horse from b3 to c3, since the rabbit has already been caught in the trap.

Alternative game ends

There are other ways the game can end other than a rabbit reaching the goal. But these are very rare:

• If a player captures all 8 of his opponent's rabbits, he wins, even if he loses his last rabbit in the same turn. Originally there was a tie when all 16 rabbits were captured, but on July 1, 2008, Syed changed this rule so the game could never end in a tie.
• If the player whose turn it is cannot make a legal move because all of his own pieces are either held or blocked, or because all possible moves are illegal because of three repetitions, that player loses.

Tactics and strategy

The English-language Arimaa Wikibook provides an overview of good gaming practices.

Fritz Juhnke (two-time Arimaa world champion) wrote the book Beginning Arimaa (English), which gives a very good introduction to the tactics and strategies that were discovered up to 2009. In 2012, the book Arimaa Strategies and Tactics (also in English) by the multiple world champion Jean Daligault was published.

Patent and trademark

Omar Syed applied for a patent on the Arimaa rulebook on October 3, 2003 and was granted US Patent No. 6981700 on January 3, 2006. Omar Syed is also the owner of the brand name "Arimaa".

Syed has made it clear that it does not intend to limit its non-commercial use. To this end, he has published a license called “The Arimaa Public License” with the stated intention of “making Arimaa a game in the public domain as much as possible while protecting its commercial use”. The license covers the use of the patent and the brand name.

Web links

Wikibooks: Arimaa Tactics and Strategy  - Learning and Teaching Materials

• Official Arimaa website (English)
• David Fotlands Arimaa program (English)

Individual evidence

1. ↑ Arimaa Wikibook , especially the chapters on tactics and strategy .
2. ^ The Arimaa Public License