Intelligence, no matter how sophisticated, must permeate actions and responses, so we realize something's going on inside the creature's virtual brain. Thus, it is essential to couple our AI routines with clever action subroutines, so we get the feeling of real intelligence. In fact, many games exaggerate this action system much like in a theater play, so the character's intentions are obvious and personality is conveyed. By doing so, the degree of intelligence sensed by the player can be much higher than the actual complexity of the core AI routines. As an example, recall the Super Mario Bros game. All types of crazy creatures filled the game world, from turtles to lizards and many other creatures. If you separate logic from the actual actions, you'll discover that these AIs were all very similar. They were either simple enemy chasing AIs or choreographed AIs. But by creating "signature" movements for each one of them, personality and perceived intelligence is enhanced.