Navegar por el directorio Ejercicio C# - Curso de Programación C# (C Sharp)

using System;
using System.IO;
using System.Threading;
using System.Collections.Generic;
using System.Diagnostics;
using System.Collections;
class SurfDirectory
{
    static int position = 0;

    static List items;

    static string directory = ".";

    static void Main()
    {
        while (true)
        {
            Console.Clear();

            items = GetItems(directory);

            ShowItems();
            ShowIndications();
            ReadKeys();
            Thread.Sleep(200);
        }
    }

    static void OpenFile(Item item)
    {
        if (item.IsFile)
        {
            Process.Start(item.Name);
        }
    }

    static void ReadKeys()
    {
        ConsoleKeyInfo key = Console.ReadKey();
        switch (key.Key)
        {
            case ConsoleKey.UpArrow:
                if (position > 0)
                {
                    position--;
                }
                break;
            case ConsoleKey.DownArrow:
                if (position < items.Count - 1)
                {
                    position++;
                }
                break;
            case ConsoleKey.Enter:
                Item item = items[position];

                if (item.IsFile)
                {
                    OpenFile(item);
                }
                else
                {
                    directory = item.Path;
                }
                break;
        }
    }

    static void ShowSelected(int i)
    {
        if (i == position)
        {
            Console.SetCursorPosition(0, position);
            Console.BackgroundColor = ConsoleColor.DarkCyan;
        }
        else
        {
            Console.BackgroundColor = ConsoleColor.Black;
        }
    }

    static List GetItems(string direc)
    {
        try
        {
            List items = new List();

            string[] directories = Directory.GetDirectories(direc);
            foreach (string directory in directories)
            {
                items.Add(new Item(directory, false));
            }

            string[] files = Directory.GetFiles(direc);
            foreach (string file in files)
            {
                items.Add(new Item(file, true));
            }

            return items;
        }
        catch
        {
            Console.WriteLine("Error reading items.");
            return null;
        }
    }

    static void ShowItems()
    {
        int i = 0;
        foreach (Item item in items)
        {
            ShowSelected(i);
            Console.WriteLine(item.Path);
            i++;
        }
        Console.BackgroundColor = ConsoleColor.Black;
    }

    static void ShowIndications()
    {
        Console.SetCursorPosition(0, 23);
        Console.WriteLine("Press arrow up for move up  | Press arrow down for move down");
    }
}

public class Item
{
    public string Path { get; set; }

    public bool IsFile { get; set; }

    public string Name
    {
        get { return Path.Substring(2); }
    }

    public Item(string path, bool isFile)
    {
        this.Path = path;
        this.IsFile = isFile;
    }
}