using UnityEngine;
using System.Collections;

public class myMove : MonoBehaviour {
    public float speed = 5f;
    Ray ray;
    RaycastHit hit;
    bool walk = true ;
    public Vector3 TargetToMove = new Vector3();
    CharacterController controller;

    // Use this for initialization
    void Start () {
     controller = (CharacterController)gameObject.GetComponent<CharacterController>();

    }
    // Update is called once per frame
    void Update () {
     if (Input.GetMouseButtonDown (0)) {
      ray = Camera.main.ScreenPointToRay (Input.mousePosition);
      Physics.Raycast (ray, out hit, 500.0f);
      TargetToMove = hit.point;
      walk = true;
     }
     if (walk) {
      move ();
     }
    }

    void move(){
     Vector3 posMove = (TargetToMove - transform.position);
     Vector3 posNormal = posMove.normalized;
     controller.SimpleMove (posNormal * Time.deltaTime * speed);
     if (posMove.magnitude < 0.1f) {
      walk = false;
     }
    }
}

using UnityEngine;
using System.Collections;

public class Gravity : MonoBehaviour {
  public Transform target;

  // Update is called once per frame
  void Update () {
   Vector3 relativePos = (target.position + new Vector3(0, 1, 0)) - transform.position;
   Quaternion rotation = Quaternion.LookRotation (relativePos);
   Quaternion current = transform.localRotation;
   transform.localRotation = Quaternion.Slerp (current , rotation, Time.deltaTime);
   transform.Translate (0, 0 , 5 * Time.deltaTime);

  }
}

если (луч падает на один слой) то {
происходит некое действие;     
}
если (луч падает на другой слой) то {
происходит некое другое действие;     
}

using UnityEngine;

public class MyNavMeshAgent : MonoBehaviour {
    NavMeshAgent agent;
   // Use this for initialization
   void Start () {
    agent = GetComponent<NavMeshAgent> ();
   }
     
   // Update is called once per frame
   void Update () {
   if (Input.GetMouseButtonDown (0)) {
     RaycastHit hit;
     if(Physics.Raycast(Camera.main.ScreenPointToRay(Input.mousePosition),out hit,100)){
      agent.destination = hit.point;
     }
    }
   }
}