As Jack Copeland and Diane Proudfoot recall in their excellent web article "Alan Turing the father of modern computing:"
"Both during and after the war Turing experimented with machine routines for playing chess: in the absence of a computer, the machine's behaviour was simulated by hand, using paper and pencil. In 1948 Turing and David Champernowne, the mathematical economist, constructed the loose system of rules dubbed the 'Turochamp'. Champernowne reported that his wife, a beginner at chess, took on the Turochamp and lost. Turing began to program the Turochamp for the Manchester Ferranti Mark I but unfortunately never completed the task. He later published a classic early article on chess programming."
In 1950 Claude Shannon's published a paper called "Programming a Computer for Playing Chess" and a couple of years later Prinz's chess program was operational. Chess playing machines therefore have a long history, from the fraudulent Mechanical Turk through IBM's Deep Blue to today's invincible Houdini - but the true pioneers were these men in the 1940s and 50s who wrote the first game AI programs.