Charles V. De Vet and Katherine MacLean’s 1981 Second Game is a stand-alone interstellar espionage novel.
Having discovered to their astonishment that they share the galaxy with another starfaring race, the Ten Thousand World Federation1 attempted to open diplomatic relations with the Veldqans. Rebuffed by the aliens, the Federation dispatched a fleet to underline the benefits of friendly relations. That fleet having been annihilated through mysterious means, Master Spy Leonard Stromberg is dispatched to the alien home world to take a closer look.
Key to his efforts: a board game.