The state of a game world is the combination of the states of all the objects within it: the state of the player (his or her location, orientation, health, inventory, etc.), the states of all NPCs (nonplayer characters—their locations, emotional states, etc.), the states of inanimate objects (which doors are locked, which buildings have collapsed, etc.), and so on. Games usually simulate a game world in order to track the evolution of its state, perhaps using level-of-detail approximations for unobserved elements of game state to reduce the complexity of doing so.
This chapter will introduce the idea of maintaining probability and possibility ...