SimpleMove with Chasing

Chasing the player is the easiest part: just rotate the enemy in the player's horizontal direction and make it move forward. But any AI must do more than this: usually the enemy must stay in an idle state when the player is too far or not visible, doing nothing or walking on a path defined by waypoints; when the player enters the chase range and/or becomes visible, chase him; when reaching a minimum distance from the player (attack range), stop and attack him. The basic script is as follows:

var speed: float = 4.5; var turnSpeed: float = 5; var chaseRange: float = 80; var attackRange: float = 2.5; private var target: GameObject; private var controller: CharacterController;

function Start(){ controller = GetComponent(CharacterController); // cache the CharacterController target = GameObject.FindWithTag("Player"); // make sure the player is tagged "Player" }

function Update(){ // find the player direction: var dir = target.transform.position-transform.position; dir.y = 0; // make it strictly horizontal var dist = dir.magnitude; // measure the distance if (dist > chaseRange){ // player too far: // idle state: do nothing or make the enemy follow a path // based on waypoints } else if (dist > attackRange){ // player in chase range but still out of attackRange: // chase state: var rot = Quaternion.LookRotation(dir); // find target direction... // and rotate gradually to it transform.rotation = Quaternion.Slerp(transform.rotation, rot, turnSpeed*Time.deltaTime); controller.SimpleMove(transform.forward*speed); // chase him! } else { // attack state: // attack the player } } You can start with this basic script and gradually implement the idle and attack modes.

NOTE: About your last question: the CharacterController only check collisions when it's moving with Move or SimpleMove; if you move it by altering its position (setting transform.position directly) or move any other object over it, collisions are ignored.