# GTAIV.EFLC.FusionFix: what the Complete Edition patch actually changes

> FusionFix is a C++ ASI plugin that patches Grand Theft Auto IV: The Complete Edition for modern systems. It installs by unpacking files into the game folder, and Linux players need a Wine DLL override before it loads at all.

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

- Repository: https://github.com/ThirteenAG/GTAIV.EFLC.FusionFix
- Website: https://fusionfix.io/iv
- Stars: 3,343 · Forks: 117
- Language: C++
- License: GPL-3.0
- Published: 2026-09-24 · Updated: 2026-09-24 · Language: en
- Canonical page: https://hysenlabs.com/projects/thirteenag-gtaiv-eflc-fusionfix

## The problem FusionFix is written against

Grand Theft Auto IV shipped in 2008 and was reissued as The Complete Edition, which bundles the base game with the Episodes from Liberty City content. The README states the project "aims to fix some issues in Grand Theft Auto IV: The Complete Edition, as well as add various new features for modern systems." That sentence is the whole scope. This is not a content mod, not a graphics overhaul pack, and not a launcher replacement. It is a patch layer aimed at a specific retail build that has aged badly on current hardware and current Windows.

The intended user is narrow. You already own the game, you have it installed from your library, and you want it to behave on a machine built long after the game was. The repository topics list asi, eflc, episodesfromlibertycity, grandtheftautoiv and gta4, which matches that audience: people running the Complete Edition and looking for a maintained patch rather than a set of unrelated mods. If you are modding a different build, or a different game entirely, the README points elsewhere. It notes the same approach is "also available for Max Payne 3 and other games" through a separate index page, which tells you the author treats this as one entry in a family of patches rather than a one-off.

The honest framing is that FusionFix is maintenance work on someone else's abandoned product. It exists because the publisher stopped. That is a real service to a specific group of players, and it is also the reason the project's support matrix is so tight.

## How the patch loads: dinput8.dll and the ASI layer

The mechanism is visible in the repository layout and in the Linux instructions. The plugin is a C++ project built with Premake (premake5.lua, premake5.exe, premake5.bat at the top level), and the shipped artifact is loaded through a proxy DLL. The README's non-Windows section is explicit about which one: "You need to tell Wine explicitly that the dinput8.dll file is to be used." That is the loader. The game imports dinput8.dll at startup; the mod supplies its own copy of that name, and from inside that process it hooks the game and applies its changes. The asi topic on the repository is the same idea in mod-loader vocabulary.

This design choice has consequences worth naming. Because the entry point is a DLL sitting next to the executable, the plugin has to be in the game's root directory, and it has to be the copy the game actually resolves. On Windows that resolution is automatic. On Wine and Proton it is not, which is why the README devotes a whole warning block to DLL overrides. The README also notes that "Proton Experimental already loads it by default, so you may skip this step," which is a useful detail: the override is not a permanent tax on every Linux user, only on those whose Proton build does not already prefer the local DLL.

The rest of the tree is build tooling for game assets: buildgxt.bat, buildimg.bat, buildshaders.bat and buildwtd.bat sit alongside data/, shaders/, text/ and textures/ directories. Those names map to the GXT text format, IMG archives, shader files and WTD textures. In other words, the project does not only patch code paths at runtime; it also rebuilds packaged game data as part of its build. That is a heavier approach than a pure memory patch, and it is why releases are versioned artifacts rather than a single DLL.

## Installing GTAIV.EFLC.FusionFix from the zip

The README gives two routes. The manual one is the shortest: install the game, download the release zip, and "unpack its contents to the game's root directory, where the exe is located." The installer route is friendlier and comes in two flavours, a web installer and an offline installer. Both are named exactly as follows in the README.

```bash
GTAIV.EFLC.FusionFixWebInstaller.exe
GTAIV.EFLC.FusionFixOfflineInstaller.exe
```

Open either one, point it at the game directory, and wait. The README warns that an error during installation is "likely due to the installer not having write access," and the fix it gives is to open the properties of the game directory, grant your system's users write permission, and apply. Do that before rerunning the installer, not after.

On Linux the same files go into the same place, but the loader needs to be told. For a one-off launch from a command line, the README shows prepending the override to the usual start command:

```bash
WINEDLLOVERRIDES="dinput8=n,b"
```

For Steam, the same value goes into the game's launch options, wrapped around the command placeholder:

```
WINEDLLOVERRIDES="dinput8=n,b" %command%
```

The README describes a second, permanent method using winecfg against the prefix Steam creates for the game, and gives the path as $HOME/.steam/steam/steamapps/compatdata/12210/pfx. In the Libraries tab you add the library name and confirm it appears with a "(native, builtin)" suffix. The README also lists a related step: install and run Protontricks, choose Grand Theft Auto IV, select the default Wineprefix, choose "Install a Windows DLL or component", search for d3dx9_43 and confirm. That last step exists because the game expects a DirectX 9 helper that modern Proton prefixes do not ship by default.

One more constraint sits above all of this. The README states that "only The Complete Edition is fully supported," and that legacy versions such as v1.0.7.0 or v1.0.8.0 additionally require a separate Legacy Addon archive, installed by unpacking it as well. If you are not sure which build you have, settle that question before you copy anything.

## Where FusionFix is the wrong tool

The support matrix is the first limitation and it is not a soft one. If your copy is a legacy build and you skip the Legacy Addon, the README's own wording implies you are outside the supported configuration. Adding the addon is a second unpack and a second thing to keep in sync with every FusionFix release, which is exactly the kind of step people forget during an upgrade.

The second limitation is platform. On Linux the plugin is inert until the DLL override is in place, and the README offers three separate ways to do it precisely because there is no single reliable one. A player who unpacks the zip, launches through Steam, and sees no change has almost certainly hit this, not a bug in the patch. The README does not document a diagnostic for that situation, so the only signal is the absence of whatever behaviour you expected.

The third is scope. This is a patch for one game's Complete Edition. If your goal is to add new missions, new vehicles or a total conversion, FusionFix is the wrong layer: it is not a content framework, and the README does not present it as one. The same applies if you play on a platform where the game itself is not available to you, since the installation instructions assume you installed it "from your library" first.

Finally, there is a maintenance caveat that applies to any patch of this kind. The repository's release history is not a steady drip. v4.0.5 landed on 2025-10-26, v5.0.0 on 2026-05-03, and v5.0.1 on 2026-05-12, with the last push to the repository on 2026-09-23. A major version boundary between 4.x and 5.x is the point where configuration and behaviour are most likely to have moved, and the README does not document a rollback procedure for a bad upgrade.

## FusionFix against a generic ASI mod loader

The obvious alternative is to treat this as a plugin and manage it with a general ASI loader plus a set of individual fixes. The difference in approach is real. A generic loader gives you a directory of independent .asi files, each doing one job, each replaceable on its own. FusionFix is the opposite: one project, one release, one version number covering a bundle of fixes and features, installed as a unit.

That trade-off cuts both ways. The bundle is easier to reason about as a whole. You install one thing at one version, and the fixes inside it were built and tested together, which matters when several of them touch the same rendering or input paths. The cost is granularity. If one fix in the bundle misbehaves on your hardware, you cannot drop just that fix and keep the rest; your options are the previous release or nothing. With separate plugins, you would remove one file.

The second difference is the data rebuild. Because the repository contains build scripts for GXT, IMG, shader and WTD assets, FusionFix ships changes to packaged game data, not only runtime hooks. A loose collection of ASI plugins typically does not. That makes FusionFix more capable for fixes that live in the data, and it also makes its releases larger and its version bumps more consequential. A generic loader also leaves you responsible for load order and for resolving conflicts between plugins that hook the same function. FusionFix absorbs that responsibility, at the price of the granularity above.

## Licence, upgrades and what a version bump costs you

The project is GPL-3.0. For a player, that changes nothing about installing or running it. For anyone who wants to reuse the source in another project, it is the usual copyleft arrangement: derivative works distributed to others have to carry the same licence, and the source has to be available. This is not legal advice, and the licence file in the repository root is the authority, not this paragraph.

The upgrade cost is the part worth planning for. Because installation is a file drop into the game root rather than a package manager, upgrading means replacing files, and there is no documented uninstall or rollback path in the README. If a new release regresses something on your machine, the recovery route is to reinstall the previous release's archive over the top, which means keeping the old zip. Two habits follow from that, both tied to this project: keep the release archive you are currently running, and read the release notes for a major bump before applying it.

The version cadence suggests when to be careful. v4.0.5 to v5.0.0 is a major boundary, and v5.0.0 to v5.0.1 is a patch. The first is where behaviour is most likely to shift; the second is where it is least likely. If you are mid-playthrough, the patch releases are the safer time to update. Configuration lives in an ini file, which is the other upgrade consideration: an ini carried over from a 4.x install may not match the keys a 5.x build expects, and the README does not enumerate the keys or their defaults.

## Conclusion

Adopt FusionFix if you run the Complete Edition of Grand Theft Auto IV on Windows and want the documented fixes and modern-system features with a single unpack into the game root; the README treats that edition as the only fully supported one. Do not adopt it if you are on a legacy build such as v1.0.7.0 or v1.0.8.0 and are unwilling to also install the Legacy Addon, or if you play on Linux and will not set a dinput8 DLL override, since the README states the plugin will not be loaded without one. Before installing, verify which edition your library actually holds, confirm write access to the game directory so the installer can finish, and read the release notes for the version you download rather than assuming every option behaves as it did in an older build.

## FAQ

### What is GTA IV FusionFix?

It is a C++ patch for Grand Theft Auto IV: The Complete Edition that, in the README's words, "aims to fix some issues" in the game and "add various new features for modern systems." It installs into the game's root directory as a plugin loaded through dinput8.dll.

### What does "eflc" mean in the context of Grand Theft Auto IV?

It stands for Episodes from Liberty City, the episodic content bundled with The Complete Edition. The repository lists it among its topics alongside episodesfromlibertycity and gta4, and the project name carries it because the patch targets that combined release.

### How do I install FusionFix in GTA IV?

Download the release zip and unpack its contents to the game's root directory where the exe is, or run the web or offline installer, select the game directory and wait. If the installer errors, the README attributes it to missing write access on the game folder.

### Is FusionFix safe?

The README does not make a safety claim either way. What it does document is a distribution route through the project's own GitHub releases, a GPL-3.0 licence, and an installer that needs write access to the game directory, so the practical check is that you downloaded from the project's release page.

### How do I install GTAIV.EFLC.FusionFix?

The README gives two routes: download GTAIV.EFLC.FusionFix.zip and unpack it to the game's root directory where the exe is, or run GTAIV.EFLC.FusionFixWebInstaller.exe or GTAIV.EFLC.FusionFixOfflineInstaller.exe, select the game directory and wait for it to finish.

## Sources

- [License: GPL-3.0](https://github.com/ThirteenAG/GTAIV.EFLC.FusionFix/blob/master/LICENSE)
- [Project website](https://fusionfix.io/iv)
- [README](https://github.com/ThirteenAG/GTAIV.EFLC.FusionFix/blob/master/README.md)
- [Releases](https://github.com/ThirteenAG/GTAIV.EFLC.FusionFix/releases)
- [ThirteenAG/GTAIV.EFLC.FusionFix on GitHub](https://github.com/ThirteenAG/GTAIV.EFLC.FusionFix)

---

Hysen Labs editorial analysis, written from the project's own repository and release notes. Cite the canonical page: https://hysenlabs.com/projects/thirteenag-gtaiv-eflc-fusionfix