How to move object when click on specific tile?

Thank you, i'm a absolute beginner for Unity3D game development. I will try it then give you respond ASAP. Sorry for my english. Thank you again :)

@ShadoX i tested your suggestion. it works for detect face of objects. But when i rotate object by 90 degrees. it gives me same result.

Example: Before rotation: result of cube is South, Up, East ... After rotation: result of cube is South, Up, East...

What i want is: Before rotation: result of cube is South, Up, East ... After rotation: result of rotated cube like (if 90 degree rotated East, Up, North)

Here is my code:

 using UnityEngine;
 using System.Collections;
 
 public class SideDetecter : $$anonymous$$onoBehaviour {
 
     // Use this for initialization
     void Start () {
     
     }
 
     public float speed = 50f;
 
     public Transform gunObj;
     // Update is called once per frame
     void Update () {
         if (Input.Get$$anonymous$$ouseButton(0)) {
             //transform.RotateAround(Vector3.zero, Vector3.up, speed * Time.deltaTime);
 
             //Debug.Log ("$$anonymous$$ouse Clicked");
             RaycastHit hit;
             Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
             if (Physics.Raycast(ray, out hit)) {
                 Debug.Log ("RayCast");
                 Vector3 inco$$anonymous$$gVec = hit.point - gunObj.position;
                 Vector3 reflectVec = Vector3.Reflect(inco$$anonymous$$gVec, hit.normal);
                 Debug.DrawLine(gunObj.position, hit.point, Color.red);
                 Debug.DrawRay(hit.point, reflectVec, Color.green);
             }
             //transform.rotation = Quaternion.FromToRotation(transform.up, hit.normal) * transform.rotation;    
             GetHitFace(hit);
         }
     }
 
     public enum $$anonymous$$CFace
     {
         None,
         Up,
         Down,
         East,
         West,
         North,
         South
     }
 
     public $$anonymous$$CFace GetHitFace(RaycastHit hit)
     {
         Debug.Log ("RayCast2");
         Vector3 inco$$anonymous$$gVec = hit.normal - Vector3.up;
 
         if (inco$$anonymous$$gVec == new Vector3(0, -1, -1)) {
             Debug.Log ("$$anonymous$$CFace.South");
             return $$anonymous$$CFace.South;
         }
 
         if (inco$$anonymous$$gVec == new Vector3(0, -1, 1)) {
             Debug.Log ("$$anonymous$$CFace.North");
             return $$anonymous$$CFace.North;
         }
 
         if (inco$$anonymous$$gVec == new Vector3(0, 0, 0)) {
             Debug.Log ("$$anonymous$$CFace.Up");
             return $$anonymous$$CFace.Up;
         }
 
         if (inco$$anonymous$$gVec == new Vector3(1, 1, 1)) {
             Debug.Log ("$$anonymous$$CFace.Down");
             return $$anonymous$$CFace.Down;
         }
 
         if (inco$$anonymous$$gVec == new Vector3(-1, -1, 0)) {
             Debug.Log ("$$anonymous$$CFace.West");
             return $$anonymous$$CFace.West;
         }
 
         if (inco$$anonymous$$gVec == new Vector3(1, -1, 0)) {
             Debug.Log ("$$anonymous$$CFace.East");
             return $$anonymous$$CFace.East;
         }
 
         return $$anonymous$$CFace.None;
     }
 }