Iain M. Banks - The Player of Games (.mobi) ~DJAUZZIEMAN~

Jernau Morat Gurgeh, a famously skilful player of board games and other similar contests, lives on Chiark Orbital, and is bored with his successful life. The Culture's Special Circumstances inquires about his willingness to participate in a long journey, though won't explain further unless Gurgeh agrees to participate. While he is considering this offer, one of his drone friends, Mawhrin-Skel, which had been ejected from Special Circumstances due to its unstable personality, convinces him to cheat in one of his matches in an attempt to win in an unprecedented perfect fashion. The attempt fails, but Mawhrin-Skel uses his recording of the event to blackmail Gurgeh into accepting the offer and insisting that Mawhrin-Skel be admitted back into Special Circumstances as well.
Gurgeh spends the next two years travelling to the Empire of Azad in the Small Magellanic Cloud, where a complex game (also named Azad) is used to determine social rank and political status. The game itself is sufficiently subtle and complex that a player's tactics reflect his own political and philosophical outlook. By the time he arrives, he has grasped the game but is unsure how he will measure up against opponents who have been studying it for their entire lives.
Gurgeh lands on the Empire's home planet of Eä, accompanied by another drone, Flere-Imsaho. As a Culture citizen, he naturally plays with a style markedly different from his opponents, many of whom stack the odds against him one way or another, such as forming backroom agreements to cooperate against him (which is allowed by the game's rules). As he advances through the tournament he is matched against increasingly powerful Azad politicians, and ultimately the Emperor himself in the final round. Faced with defeat, the Emperor attempts to kill Gurgeh, but is himself killed by a shot from his own weapon, deflected by Flere-Imsaho (who later refuses to tell Gurgeh if it was coincidental).
Flere-Imsaho reveals that Gurgeh's participation was part of a Culture plot to overthrow the corrupt and savage Empire from within, and that he, the player, was in fact a pawn in a much larger game. Although Gurgeh never discovers the whole truth, it is ultimately revealed to the reader that Flere-Imsaho was the same drone as Mawhrin-Skel, who was also the narrator of the novel itself.