The Player of Games

The Player of Games is a science fiction novel by Iain M. Banks, and the second published to feature The Culture, his fictional utopian society. It is widely considered the most immediately accessible of the Culture books, and is therefore perhaps a better introduction to the sequence than the earlier Consider Phlebas.

Warning: Wikipedia contains spoilers

Jernau Morat Gurgeh, a master gamesplayer from the Culture, is bored with life. The Culture's Contact section suggests that he goes to participate in a games tournament in a savage alien empire, the Empire of Azad, where a complex game is used to determine social rank and political status. He belatedly discovers that his participation is essentially a Culture takeover plot, and that he, the player, was in fact a pawn in a larger game.