It is not being argued that players just do respond to the non-mathematical properties of the game but that they ought to take them into account, hence that even a normative theory—a theory of the strategy of games—must recognize that rational players may jointly take advantage of them. And even when one rational player realizes that the configuration of these details discriminates against him, he may also rationally recognize that he has no recourse—that the other player will rationally expect him to submit to the discipline of the suggestions that emanate from the game's concrete details and will take actions that, on pain of mutual damage, assume he will co-operate.

DEFINE: Defines a normative game theory that extends beyond mathematical payoffs to include the concrete, non-mathematical properties of a game, which rational players are obligated to consider.

Thomas C. Schelling, The Strategy of Conflict, loc. 257