if (Input.GetKeyDown("Escape")){
    Application.Quit()
   }

          Transform curTransform; - обявляют переменную с именем curTransform типа Transform (хранит размеры, координаты, углы поворота)
         curTransform = gameObject.GetComponent<Transform>(); - привязывают к переменной компонент Trasform
         curTransform = gameObject.transform; - присваивают значение Transform

ArgumentException: You are not allowed to call GetComponent when declaring a variable.
Move it to the line after without a variable declaration.
Don't use this function in the constructor or field initializers, instead move initialization code to the Awake or Start function.
steps..ctor () (at Assets/steps.js:8)

var controller : CharacterController = GetComponent(CharacterController);
var FootSteps : AudioClip [];
private var StepTime : float = 0;
var audioSource : AudioSource;
private var stepping : boolean = false;

function Update () {
if(controller.isGrounded){
if(!stepping){

if (Input.GetButton("Vertical") || Input.GetButton("Horizontal")){
StepTime = 0.5;

}

}
}
}

function footfall(){
stepping = true;
audioSource.PlayOneShot (FootSteps[Random.Range(0,FootSteps.length)]);
yield WaitForSeconds (StepTime);
stepping = false;
}