El Ajedrecista

El Ajedrecista () is an automaton built in 1912 by Leonardo Torres y Quevedo, one of the first autonomous machines capable of playing chess. 
As opposed to the human-operated The Turk and Ajeeb, "El Ajedrecista" was a true automaton built to play chess without human guidance. It played an endgame with three chess pieces, automatically moving a white king and a rook to checkmate the black king moved by a human opponent.
The device could be considered the first computer game in history. It created great excitement when it made its debut, at the University of Paris in 1914. It was first widely mentioned in "Scientific American" as "Torres and His Remarkable Automatic Devices" on November 6, 1915.
The automaton does not deliver checkmate in the minimum number of moves, nor always within the 50 moves allotted by the fifty-move rule, because of the simple algorithm that calculates the moves. It did, however, checkmate the opponent every time. If an illegal move was made by the opposite player, the automaton would signal it.
Technical description.
Its internal construction was published by H. Vigneron. The pieces had a metallic mesh at their base, which closed an electric circuit that encoded their position in the board. When the black king was moved by hand, an algorithm calculated and performed the next best move for the white player.
In the first version, the pieces were plugged into the board, and the game states of check and checkmate were signaled with light bulbs. Leonardo's son Gonzalo made an improved chess automaton based on El Ajedrecista in 1920, which made its moves via electromagnets located under the board. It also included a sound effect, with a voice recording announcing checkmate when the computer won the game.
 Both are still working and are on display at the "Museo Torres Quevedo" in the "Escuela de Ingenieros de Caminos, Canales y Puertos" in Madrid.