Arimaa /əˈriːmə/ ⓘ (ə-REE-mə) is a two-player strategy board game that was designed to be playable with a standard chess set and difficult for computers while still being easy to learn and fun to play for humans.

It was invented between 1997 and 2002 by Omar Syed,[1][2][3] an Indian-American computer engineer trained in artificial intelligence.

Syed was inspired by Garry Kasparov's defeat at the hands of the chess computer Deep Blue to design a new game which could be played with a standard chess set, would be difficult for computers to play well, but would have rules simple enough for his then four-year-old son Aamir to understand.

After eleven years of human dominance, the 2015 challenge was won decisively by the computer (Sharp by David Wu).

These are, in order from strongest to weakest: one elephant (), one camel (), two horses (), two dogs (), two cats (), and eight rabbits ().

These may be represented by the king, queen, rooks, bishops, knights, and pawns respectively when one plays using a chess set.

The main object of the game is to move a rabbit of one's own color onto the home rank of the opponent, which is known as a goal.

The second diagram, from the same game as the initial position above,[10] helps illustrate the remaining rules of movement.

[12] As part of the conditions of the prize, the computer program must run on standard, off-the-shelf hardware.

Following the second match, Syed changed the format to require the software to win two out of three games against each of three players, to reduce the psychological pressure on individual volunteer defenders.

Also Syed called for outside sponsorship of the Arimaa Challenge to build a bigger prize fund.

In the first five challenge cycles, David Fotland, programmer of Many Faces of Go, won the Arimaa Computer Championship and the right to play for the prize money, only to see his program beaten decisively each year.

In 2010, Mattias Hultgren's bot Marwin edged out Clueless in the computer championship.

In 2012 a new challenger, Briareus, became the first program to defeat a top-ten player, sweeping all three games from the fifth-ranked human.

Sharp dominated the pre-Challenge screening against human opponents, winning 27 of 29 games.

[12] Wu published a paper describing the algorithm and most of ICGA Journal Issue 38/1 was dedicated to this topic.

[14] The algorithm combined traditional alpha–beta pruning (changing sides every 4 ply) with heuristic functions manually written while analysing human expert games.

[15] After DeepMind's AlphaZero mastered Go, Chess, and Shogi simply by playing itself, Omar Syed announced a $10,000 prize for the creation of such an Arimaa bot which could win a 10-game match against Sharp.