Clock.cs

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Clock : MonoBehaviour {

    public Transform hourTransform, minuteTransform, secondTransform;

    public bool sweeping;

    void Update () {
        if (sweeping) {
            UpdateSweeping ();
        }
        else {
            UpdateTicking ();
        }
    }

    void UpdateSweeping () {
        hourTransform.localRotation =
            Quaternion.Euler(0, (float)DateTime.Now.TimeOfDay.TotalHours * 30, 0);
        minuteTransform.localRotation =
            Quaternion.Euler(0, (float)DateTime.Now.TimeOfDay.TotalMinutes * 6, 0);
        secondTransform.localRotation =
            Quaternion.Euler(0, DateTime.Now.Second * 6, 0);
    }

    void UpdateTicking () {
        hourTransform.localRotation =
            Quaternion.Euler(0, DateTime.Now.Hour * 30, 0);
        minuteTransform.localRotation =
            Quaternion.Euler(0, DateTime.Now.Minute * 6, 0);
        secondTransform.localRotation =
            Quaternion.Euler(0, DateTime.Now.Second * 6, 0);
    }

}