Throughout Tinker, Tailor, Soldier, Spy, an important theme is the game-like nature of the world of intelligence. The people who work in the Circus live in a separate world, where they have nicknames for everything from wiretapping to murder. Those who work inside the Circus put themselves against the rest of the world, trying to outwit everyone, including their allies. The detached and cynical attitude of men like Haydon illustrates how emotionally detached people become from their actions. To them, the world of intelligence is a highly-addicted game in which they must always emerge on top. For those who have been retired from the Circus, being unable to take part in this game is a torture. Connie Sachs, Jim Westerby, and Smiley all regret that they are excluded from the great game of intelligence, even if they only played minor roles.

At the beginning of the novel, Smiley is utterly bored. He is excluded from the game of intelligence gathering through no fault of his own. His wife leaves him, he spends his days trying to avoid certain people, and he invents chores to occupy his time, all while trying to satisfy his busy mind with small bits of spy tradecraft that no longer mean anything.