How to play GTA IV's Singleplayer COOP

How to get GTA IV Co-Op Working Through GFWL in 2023
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1. Go to https://gtaforums.com/topic/976691-gta-iv-downgrader/ and download the latest version of the downgrader
2. Boot the downgrader in administrator mode, select your GTA IV directory (Steam: This PC/Windows-SSD(C:)/Program Files (x86)/Steam/steamapps/common or wherever else you got it from illegally)
3. Move the game directory to anywhere you would like (That isn't the original Steam directory)
4. Select to downgrade to version 1.0.8.0
5. Configure the downgrade for GFWL
6. Select the radio downgrader by Sneed
7. Select the "Old Vladivostok" option
8. For mods leave dsound and ZolikaPatch checked, but also select the ZMenu (needed to access co-op feature)
9. Create a backup if you would like (I have not tried so i don't know or if it works)
10. We started from absolute scratch so I do not know how save downgrading works, do it if you would like to transfer your progress.
11. Select the reccomended command line (but not the "also include" box below it).
12. Allow the downgrader to finish (will probably take 20-30 minutes)
13. Run the downgrader again without administrator mode and select the same options as previous (game directory will now be wherever you put it instead of steam) (For whatever reason directX was not installed the first time for us in admin mode, and was fixed when ran without admin mode, it may work perfectly the first time with admin mode for you. The downgrader can get stuck if ran without administrator access)
14. Boot GTA IV using the executable "PlayGTAIV.exe" not the normal application.
15. Log in to GFWL using a microsoft login and a valid product key. You will automatically log in if the key was entered back when GTA IV used GFWL before moving to the Rockstar launcher. If you did not play GTA IV before this point, one player can use the steps described here: https://www.youtube.com/watch?v=QKEtv91j_xk (THIS ONLY WORKS FOR ONE PLAYER)
Other players must get a new GFWL key generated. This can be done buy buying a Kane and Lynch: Dead Men key from G2A: https://www.g2a.com/kane-and-lynch-dead-men-steam-key-global-i10000044418004 or buy FlatOut: Ultimate Carnage from Steam. Get the key from Manage (gear symbol) > Manage > CD Keys, then use that key on GTA IV's GFWL login
16. Once in game and in free mode, pull up the phone, enter a Multiplayer LIVE Party Mode session.
17. After loading in, press F7 (or M, whatever the hotkey is set to in the config) to open the mod menu, and navigate to MP Functions > Game Tweaks > SP Co-Op > Quick Start from Savegame > and either Serverside Quick Start for HOST player or Clientside Quick Start for JOINING player(s).
(Note: Must have a Num pad to navigate the mod menu. If you are on a laptop or do not have a numpad on your keyboard, use this https://www.mediafire.com/file/gfbobklcqar0487/Zmenu+no+numpad+hotkey+ini+file+v1.rar/file to navigate the mod menu from a num-padless keyboard. (M to open/close the menu, J and U to go up and down respectively, O to accept and I to return)).

AS HOST:
After pressing Serverside Quick Start, pause the game with esc and press the left arrow key once. DO NOT PRESS "Game" with the mouse. Click "Load" and load whatever save file you want to play on
Go back to the "Game" section, go into LIVE and invite your friends to the game session.

AS CLIENT:
After pressing Clientside Quick Start, wait for an invite from the host player and join it from the LIVE menu.
Once all players are connected, the host can begin missions or play in SP free mode.