How to get the difference between two GAME TIME?

private DateTime Begin;
public const int TimeScale = 60;
public const int UpdateRealSec = 1;

private void Awake()
{
    Begin = new DateTime(1, 1, 1, 7, 00, 0);
}

public DateTime GetGameTime()
{
    long gameTickDiff = (DateTime.Now - Begin).Ticks / TimeScale;
    return new DateTime(Begin.Ticks + gameTickDiff);
}

call action by update()

Update()
{
    var time = GetGameTime();
    bool overAnHour; // check time over one hour , call action
    if(overAnHour)
    {
       foreach(var dic in TimeRegDic)
       {
          dic.Key.Invoke();
       }
    }
}