 Game forms may be seen as spaces where players can operate. A game, however, is not fully determined by its game form alone. Rather, the players involved may import additional features relevant for game play. Players can, for instance, be limited in their powers of observation, either by aspects of the game structure or through cognitive limitations. The most striking added feature, however, is that players have preferences. Agents not only observe the world or act in it. While these describe mere kinematics of a game, agents also evaluate current state and various possible futures. Being driven by preferences, it is such evaluations that are the moving force behind player’s choices. Preference, hence, take a prominent explanatory role for true game dynamics.