PlayerAttack.js

//PlayerAttack.js
#pragma strict

var hitDistance : float = 1.5;

var attackStrength = 50.0;  //damage dealt to zombie
var attackForce = 800.0;    //determines the knockback on a zombie
var attackCounterSet = 10;
var attackCounter = attackCounterSet;

function FixedUpdate () {
    if(attackCounter > 0){
        attackCounter--;
    }

    if(Input.GetMouseButtonUp(0) && attackCounter <= 0){   //if left click and timer is 0, attack
        attackCounter = attackCounterSet;
        Attack();

    }
}

function Attack(){



    var cam : Camera = Camera.main;
    var ray : Ray = cam.ScreenPointToRay(Vector3(cam.pixelWidth /2, cam.pixelHeight / 2, 0));
    var hit : RaycastHit;
    if (Physics.Raycast(ray, hit)){

        if((hit.collider.gameObject.tag == "Zombie") && (hit.distance <= hitDistance)){  //if distance within range && is zombie
          hit.collider.GetComponent(ZombieScript).adjustHealth(attackStrength);     //adjustHealth
          hit.rigidbody.AddRelativeForce(0, 0, -attackForce);   //force back

            if(hit.collider.GetComponent(ZombieScript).health <=0){
            //die code
            Destroy(hit.collider.gameObject);

            }
        }


    }



}

function OnGUI(){
GUI.Box(new Rect (Camera.main.pixelWidth/2-25, Camera.main.pixelHeight/2-25, 50, 50), "X");
}