Quickstart Guide

Prerequisites

IW4x is not a game on its own. It requires Call of Duty: Modern Warfare 2 (2009) to be installed.
If you do not own the game yet, please first buy and install it via Steam.

Important Compatibility Notice

As of 2025, Call of Duty: Modern Warfare 2 is also available via the Microsoft Store.
Please note: IW4x is not compatible with this version. Only the latest Steam version of the game is supported.

Additionally, we frequently see issues caused by pirated copies, including bugs and crashes.
We do not support pirated versions and will offer no assistance for them.

Iw4x needs to be installed in the same directory where Call of Duty: Modern Warfare 2 is installed.
Usually, the path to this directory is:

Windows

 C:\Program Files (x86)\Steam\steamapps\common\Call of Duty Modern Warfare 2

Linux

 $STEAMLIBRARY/steamapps/common/Call of Duty Modern Warfare 2

MacOS

 ~/Library/Application Support/Steam/steamapps/common/Call of Duty Modern Warfare 2

Finding your Modern Warfare 2 installation

If you have trouble to find the install directory, you can use your Steam Library as help:

1. Open Steam and go to your LIBRARY

2. Right-click on Call of Duty: Modern Warfare 2 (2009) - Multiplayer

3. Select Manage > Browse local files

Installing IW4x

Once you’ve located the Modern Warfare 2 game directory, you are ready install IW4x.
The simplest way is by using the IW4x launcher, which will download and install all required files automatically.

1. Get the launcher from GitHub

   Download for Windows Download for Linux

2. Move it into your Modern Warfare 2 directory

3. Double-click the launcher to start the installation

Windows protected your PC

Windows may display a warning the first time you run iw4x-launcher.exe.
This happens simply because the file isn’t commonly seen on Windows systems (not because it’s unsafe).
It’s completely normal behavior and the launcher is safe to use.
If you see the warning, you can safely click on More info and then Run anyway.

(And yes, the warning can be removed, but it requires a Microsoft code-signing certificate, which costs a lot of money.)

Using the Launcher

Note

We recommend using the launcher every time you play IW4x.
It will automatically download any updates and provides additional customization options.

Once you’ve installed IW4x, you should see the following folder and files in your game directory:

• DirectoryCall of Duty: Modern Warfare 2

  • Directoryiw4x/

    • …
  • Directorylauncher

    • cache.json
    • config.json
    • log.log
  • iw4x.exe
  • iw4x-launcher.exe
  • … other files and folders

If you open config.json in a text editor (such as Notepad), you’ll see something like this:

launcher/config.json

{
  "update_only": false,
  "skip_self_update": false,
  "force_update": false,
  "args": "-stdout",
  "offline": false,
  "testing": false,
  "disable_art": false,
  "dxvk": false
}

These are configuration values you can adjust to suit your preferences (more details about each option on GitHub).
The most important part is the "args" configuration: The arguments you add there will be used whenever you start the game via launcher.

For example, if you want to play offline against bots using the Bot Warfare Mod, you could set "args" like this:

{
  "args": "-stdout -disable-mod-unloading +set fs_game mods/mp_bots",
  "offline": false,
  "testing": false,
  "disable_art": false,
  "dxvk": false
}

Now, each time you launch the game via the launcher, it will automatically load the mod!