Vidreven edited the summary of The Player of Games Tuesday, March 23, 2010.
Jernau Morat Gurgeh lives on Chiark Orbital, and is bored with his successful life. The Culture's Special Circumstances (SC) section suggests that he travel to participate in a games tournament in a distant and isolated alien civilization, the Empire of Azad. In the Empire, a complex game (also named Azad) is used to determine social rank and political status. At the same time, he is blackmailed by an ex-SC drone into accepting the assignment so that he can use SC's need of him as a lever to have the drone accepted back into Special Circumstances. This drone, Mawhrin-Skel, tempted Gurgeh into cheating in a game, and uses its records of Gurgeh's acquiescence as its weapon.
The game itself is sufficiently subtle and complex that a player's tactics come to reflect their own political and philosophical outlook. As a Culture citizen, Gurgeh naturally plays with a style markedly different from his opponents, and gradually he finds that his (and, by extension, the Culture's) values make for an extremely successful strategy. As he plays against increasingly powerful Azad politicians, Gurgeh ultimately plays against the Emperor of Azad. Belatedly, he discovers that his participation is part of a Culture plot to overthrow the corrupt and savage Empire, and that he, the player, is in fact a pawn in a much larger game. The novel climaxes in the final round of the Azad contest when, faced with defeat, the Emperor of Azad attempts to kill Gurgeh.
Although Gurgeh never discovers the whole truth, it is ultimately revealed to the reader that even the blackmail that forced him to accept the mission was almost certainly carried out with the knowledge and permission of some faction within Special Circumstances itself.