FusionFix 4.0 Turns GTA IV on PC Into the Definitive Edition

Windom Earle

Windom Earle

Member

FusionFix is a fan-made mod that essentially turns the broken PC port of GTA IV into a faithful remaster. It fixes long-standing bugs, restores missing console features, and adds entirely new graphical and quality-of-life improvements.




New Graphical Features

  • Sun shafts (God rays).
  • Volumetric fog with natural horizon blending and better draw distance.
  • Extended sun reach for more realistic lighting.
  • Improved bloom and DOF + motion blur that scale correctly with resolution.
  • Project 2DFX for denser, more realistic distant lights.

Major Fixes & Restorations

  • Graphics restored from console versions: proper gamma/contrast, working volumetric lights, soft particles, stronger vehicle reflections, working mirror reflections, and emissive building lights.
  • Bug fixes: rain visibility restored, water rendering improved, z-fighting eliminated, model fading fixed, shadows reworked, and anti-aliasing options added.
  • Performance improvements: faster load times, smoother cutscenes at higher frame rates, working mouse input, and Vulkan (DXVK) now comes with the mod integrated for better performance.

Quality-of-Life Additions

  • Modloader (Fusion OverLoader): makes installing/uninstalling mods easy without overwriting files.
  • Camera options: adjustable recenter delay, fixes for stutter and zoom issues, optional shake removal.
  • Gameplay tweaks: always-run toggle, indicators in vehicles, better sniper controls, transparent map, and cheat codes for Niko's gloves/haircut.
  • Customizability: sliders for FOV, depth-of-field, and motion blur, plus controller icon packs (including Steam Deck).
  • Optional seasonal events like winter snow and Halloween mode.
github.com

Releases · ThirteenAG/GTAIV.EFLC.FusionFix

This project aims to fix or address some issues in Grand Theft Auto IV: The Complete Edition - ThirteenAG/GTAIV.EFLC.FusionFix
github.com github.com

important: installation instructions (read to the end)
After downloading the game (no mod yet), I recommend to first add these launch options in steam: -availablevidmem 32768 -nomemrestrict -norestrictions (Change video memory value depending on your VRAM - e.g. 1024 * 12 for 12GB GPU)
After that, run the game once and set your resolution. The game will probably crash. This is fine.

After that just install the mod, it is extremely easy. Just refer to the readme

Note: After starting the game, you will usually get some legacy social club/GFWL login prompt (the game is in full screen at that point, I am not talking about the rockstar launcher). Just ignore it, it will go away after a few seconds. edit: to be clear, you will still have to log into the rockstar launcher as with every Rockstar game.

The mod will work now and you can change the settings in the different menus to your liking. The video has great explanations on what the different settings do and what they look like. Be sure to switch to Vulkan for performance improvements and stutter fixes (HUGE).
---
Also maybe consider donating to the devs, an insane amount of work went into this undoubtedly. (I am not affiliated with this in any way shape or form)
 
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Wow I never noticed that the skyscrapers didn't even render at certain points.

This mod is a crazy improvement, awesome work.
 
Its a very good mod but I think the game's graphics need a lot of fixes too. Character models, textures, and assets in general. The game it's too old at this point. There are some good mods out there that improve the look with textures and such but it's definitely time consuming

But I am glad that the community is fixing this game, is one of my favorites
 
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They've also done a whole promotional website which shows off the majority of the graphical features.
fusionfix.io

Fusion Fix for GTAIV: The Complete Edition

A comprehensive modification that fixes technical issues and enhances the Grand Theft Auto IV experience.
fusionfix.io fusionfix.io





This mod was always required to make the PC version playable but this new update is insane.
 
I used FusionFix to play GTA IV recently. I highly recommend using this mod if you're going to play GTA IV on PC. Made me realize how amazing GTA IV is, my second fav of the franchise.

After watching that video, I'm jumping back on the Lost and Damned DLC! I never really played it back in the days.
 
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If it's open source then there is zero reason for Rockstar not to use this in their inevitable remaster.
 
I have a slightly older version of this because the new ones would mess up the night shadows with the cars and the headlight shadows.

Did they fix that?
 
I have added some installation instructions to the OP. The mod itself is easy to install but there are still some tricks I recommend following because the PC version is so finicky.
 
nkarafo said:
I have a slightly older version of this because the new ones would mess up the night shadows with the cars and the headlight shadows.

Did they fix that?
Click to expand...
This new version looks like it's added those back as "Extended Night Shadows" in the last options screen, it has three options, off, lampposts and lampposts+headlight
 
This doesn't happen to fix the radio does it?

For some reason I could never get the radio station mods to work and I miss OG Vladivostok FM.
 
Wow the volumetric fog is amazing, just saw it for the first time. The vanilla game always looked off when it had the weather change to foggy weather without actual fog appearing.
 
I have to confess, I never yet to finish GTAVI but my PS3 died before I got the chance to do so. Now that I got it for PC, I seem to can't bring myself to play the game.
 
Going crazy with the distance sliders in GTA4 does cause issues with the grass in the game. So far there is no solution to fix it.
Here is an explanation:
However the grass is kinda shitty and spawns in very late anyway.
 
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I haven't played this game since launch and I remember more about it than GTAV which I played a few years ago. The writing and characters are night and day better. The DLC rules too.
 
Amazing stuff, GTA4 is a brilliant game and in my opinion the best in the series, im currently playing this on the Ally with the last version of Fusion fix so will give this version ago.
 
I didn't realize there is an update. Tbh, I'm not even sure which version of Fusion I currently use, but it is fantastic. Highly recommend checking this out if you haven't yet.
 
Windom Earle said:
-availablevidmem 32768 -nomemrestrict -norestrictions (Change video memory value depending on your GPU)
Click to expand...

YCoCg said:
Use this for the radio content, it's an installer and you can choose what you want.
github.com

Release IV-RR-23-05-2025 · Tomasak/GTA-Downgraders

Bug fixes Restored The Classics and The Beat 102.7 from pre-cut files
github.com github.com
Click to expand...

Windom Earle said:
After that just install the mod, it is extremely easy. Just refer to the readme
Click to expand...

Did all this and and works like a charm. This mod really shines, the game looks beautiful and everything just seems to work as intended.
I never dared to try modding GTA IV. In the tutorials a few years ago, it always seemed like a pain in the ass, but this is just brilliant. Easy to install, doesn't distort the game, and simply turns the PC version into the game I know and love from the PS360 era.

Thank you for this thread, I'm staring a new game now.

Windom Earle said:
Also keeping View Distance and Detail Distance at default settings is still recommended if you want the game to spawn grass as intended.
Click to expand...
What is default? My settings were maxed out right from the start.
 
Kupfer said:
What is default? My settings were maxed out right from the start.
Click to expand...
I think default is 21/30. But to be honest, I would not bother. The improvements in view distance outweigh the issues with the grass. See the video I posted a few posts above if you want a detailed explanation. So if you have the hardware for it, go crazy on the view distance and detail distance.

I have also removed this note on the grass from the OP as it is just confusing.
 
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Tarnpanzer said:
Did not know that the PC Version was such a downgrade compared to console.
Click to expand...
One of the worst ports of all time. An insane amount of bugs/downgrades and absolutely terrible performance. To this day vanilla GTA4 will stutter like crazy on 2025 top of the line hardware.
So this mod is really an awesome achievement.
 
View distance is still the most CPU intensive setting. To get a locked 144fps in certain parts of the city I need to tone it down (9800x3d)
 
Hell yeah. I've been wanting to replay GTA IV for years. Haven't played it since Gay Tony released. Might finally be time.
 
Windom Earle said:
I think default is 21/30. But to be honest, I would not bother. The improvements in view distance outweigh the issues with the grass. See the video I posted a few posts above if you want a detailed explanation. So if you have the hardware for it, go crazy on the view distance and detail distance.

I have also removed this note on the grass from the OP as it is just confusing.
Click to expand...
Going for 75/100 for both, view distance and detail distance for now.

The game can still drop to ~80fps @ 1440p with a 5800X and a 5070ti.

PKdVAVQeRhHXAhk6.jpg


Can someone tell me why I have just like 53fps and only 22% CPU and 26%?

Why doesn't my PC ramp up those numbers?
 
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Kupfer said:
Going for 75/100 for both, view distance and detail distance for now.

The game can still drop to ~80fps @ 1440p with a 5800X and a 5070ti.
Click to expand...
View distance still hammers the CPU because the game will pretty much render the whole map I think. :messenger_grinning_sweat:
With 9800x3d it can "drop" to 120 (so far) but I just want a locked 144 so I am also going to reduce view distance. (Detail distance seems to be ok at 100 for me). I am not GPU limited with a 5090 at 4k.
 
Kupfer said:
Going for 75/100 for both, view distance and detail distance for now.

The game can still drop to ~80fps @ 1440p with a 5800X and a 5070ti.
Click to expand...
Detail Distance is the hidden killer, it's just rendering all the small objects and dirt/trash. One of the Fusion Fix devs said it's best to keep Detail Distance just a bit higher than Draw Distance, around 5 or so, so if you have 75 Draw Distance, then set Detail Distance to 80. Going too far over the Draw Distance means the game is rendering all those small objects and trash but you can't see them.
 
Solrac said:
No luck. I was only able to launch the game after installing Social Club and logging in. That being said, the game looks fantastic — at max settings @ 2K using the Vulkan API, it works like a charm
Click to expand...
You mean the Rockstar Launcher? Afaik Social Club is not even a thing anymore.
It was a nightmare with GTA4 for a long time. Wait: there was also Games for Windows Live. That was the real nightmare.
 
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4 is one of those games I wish I enjoyed but I just can't have fun with.

The fact that it gets so much mod support and DXVK makes it run like a dream means any fan can keep returning to it year after year.
 
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