RaycastHit hit;  

if (Physics.Raycast(ray,out hit, Mathf.Infinity))

GameObject o = hit.collider.gameObject;

hit.collider.gameObject.GetComponent<_имя_скрипта_>()._публичная переменная или функция

MyScript _script;

_script = GetComponent<MyScript>();

_script.foo +=1;

public class mainObject: monobehaviour{  
public virtual void DoFoo(){  
}
}

public class childObject: mainObject{  

public override void DoFoo(){  

}

}

    public GameObject self;
  private Mob_stats ml=self.GetComponent<Mob_stats>();

public class Monster_Ai : MonoBehaviour {
  //выбраный обьект
  public Transform target;
  public GameObject self;
  private Mob_stats ml=self.GetComponent<Mob_stats>();

  private bool tru_target = false;
   
   
  void awake(){

  }
  // Use this for initialization
  void Start () {

  }

  // Update is called once per frame
  void Update () {
/*  if (self.GetComponent<Mob_stats>().agr>=10)
   {
    if (Vector3.Distance(target.position,transform.position) < GetComponent<self.Mob_stats>().attack_radius)
   {
     tru_target=true;
   }
    if (tru_target==true)
    {
    Debug.DrawLine(target.position,transform.position,Color.red);
     if (Vector3.Distance(target.position,transform.position) > GetComponent<self.Mob_stats>().attack_distance)
     {
     
    transform.rotation=Quaternion.Slerp(transform.rotation,
                              Quaternion.LookRotation(target.position-transform.position),
                              GetComponent<self.Mob_stats>().rot_speed*Time.deltaTime);
    transform.Translate(Vector3.forward *GetComponent<self.Mob_stats>().move_speed* Time.deltaTime,Space.Self);
     }
      
    }
    if (Vector3.Distance(target.position,transform.position) > GetComponent<self.Mob_stats>().max_attack_radius)
   {
     tru_target=false;
     GetComponent<self.Mob_stats>().agr=GetComponent<self.Mob_stats>().s_agr;
   }
   }  
    
   
*/    }
}

GUI.Box (boxEnergy, _energy + "%");