Most game behavior is written using scripts instead of rules. Rules are declarative representations that, given variables in the game, encode relationships and facts about the game. From these facts one can reason about truth in the game world. Scripts are imperative representations: they provide a set of instructions that are used to process game variables and compute some conclusion. Scripting is more intuitive for game designers and developers to work with. It is easier to conceptualize and write a script that says: "go right, go left, turn around twice, go straight, then fire your gun..." then it is to formulate a set of rules that could shape an entities movement to the same effect.