Look at this mess

// Learn more about F# at http://fsharp.org
open System
open System.Diagnostics
open System.IO
open System.Threading
open System.Security.Principal
open Microsoft.Win32

open Icons

// defining strings hue hue hue
let staticDir = Path.GetFullPath("./static")
let dllPath = Path.Combine(staticDir, "imageres.dll")
let bgpath = String.Format("/c reg add \"HKEY_CURRENT_USER\Control Panel\Desktop\" /v Wallpaper /t REG_SZ /d %s /f", Path.Combine(staticDir, "images\757.png"))
let readMe = Path.Combine(staticDir, "readme.txt")
let imageresBackup = Path.GetFullPath("%systemdrive%\\DarkTheme\\backup\\imageres_original.dll")
let newDir = Path.GetFullPath("%systemdrive%\\DarkTheme")
let backupDir = Path.GetFullPath("%systemdrive%\\DarkTheme\\backup")
let iconDir = Path.GetFullPath("./static/icons/new")
let newIconDir = Path.GetFullPath("%systemdrive%\\DarkTheme\\icons")
let notAdmin = "Please run this app as an admin for it to work, thanks :D \nThis window will close in 5 seconds"
let countdown = [4; 3; 2; 1; ]

if not(WindowsPrincipal(WindowsIdentity.GetCurrent()).IsInRole(WindowsBuiltInRole.Administrator)) then
    Console.WriteLine(notAdmin)
    Thread.Sleep(1000)
    for n in countdown do
        printfn "_________________________|%d" n
        Thread.Sleep(1000)
    Environment.Exit(5)
// kill explorer
let closeexplo = Process.Start("cmd", "/c taskkill /im explorer.exe /f")
Thread.Sleep(500)
// changes background to pure black
Console.WriteLine("Changing background")
let changebg = Process.Start("cmd", bgpath)
let forcebg = Process.Start("RUNDLL32.EXE", "user32.dll,UpdatePerUserSystemParameters")
Thread.Sleep(500)
if not(Directory.Exists(newDir)) then
    Directory.CreateDirectory(newDir) |> ignore
if not(Directory.Exists(backupDir)) then
    Directory.CreateDirectory(backupDir) |> ignore
// create backup
if not(File.Exists(imageresBackup)) then
    File.Copy(Path.Combine(Environment.SystemDirectory, "imageres.dll"), imageresBackup)
// copy icons to C drive
if not(Directory.Exists(newIconDir)) then
    Directory.CreateDirectory(newIconDir) |> ignore
for i in iconName do
    File.Copy(iconDir + i + ".ico", newIconDir + i + ".ico")
    if not(Registry.CurrentUser.GetValue("Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\." + i + "\UserChoice", "ProgID") = null) then
        let userChoice = Registry.CurrentUser.GetValue("Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\." + i + "\UserChoice", "ProgID").ToString()
        let name = Registry.ClassesRoot.GetValue(userChoice + "\DefaultIcon", "(Default)").ToString()
        Registry.ClassesRoot.SetValue(name, newIconDir + i + ".ico")
// changing registry
let openexplo = Process.Start("cmd", "/c explorer.exe")
Thread.Sleep(500)
Console.WriteLine("Success, closing in 5 seconds")
Thread.Sleep(1000)
for n in countdown do
    printfn "_________________________|%d" n
    Thread.Sleep(1000)
Environment.Exit(0)