Mod loaders explained
SKSE, Fabric, ScriptHookV, BepInEx, UE4SS, ReShade… what each one is, which games use it, and where to get it safely.
A passthrough mod is really two mods, one in each game. Each needs a mod loader: a small, well-known tool that lets a game load extra code. You install the loader once, and mods plug into it.
The common ones
| Loader | Games | What it is | Get it from |
|---|---|---|---|
| SKSE64 | Skyrim SE/AE | Skyrim Script Extender; loads native plugins | skse.silverlock.org |
| Address Library | Skyrim SE/AE | Lets plugins work across Skyrim versions | Nexus Mods (Skyrim SE) |
| F4SE | Fallout 4 | Fallout 4 Script Extender | f4se.silverlock.org |
| xNVSE | Fallout: New Vegas | New Vegas Script Extender | github.com/xNVSE/NVSE |
| Fabric | Minecraft Java | Lightweight Minecraft mod loader | fabricmc.net |
| NeoForge / Forge | Minecraft Java | The other big Minecraft mod loaders | neoforged.net / minecraftforge.net |
| ScriptHookV | GTA V (story mode) | Loads scripts and ASI plugins | dev-c.com/gtav/scripthookv |
| BepInEx | Unity games (Valheim, Subnautica, ULTRAKILL, Megabonk…) | General Unity plugin loader | github.com/BepInEx/BepInEx |
| MelonLoader | Unity games | Another Unity loader | github.com/LavaGang/MelonLoader |
| OWML | Outer Wilds | Outer Wilds Mod Loader, via its mod manager | outerwildsmods.com |
| UE4SS | Unreal Engine 4/5 games | Lua scripting and C++ mods for Unreal games | github.com/UE4SS-RE/RE-UE4SS |
| ReShade | Most DirectX/OpenGL/Vulkan games | Post-processing injector; with add-on support it can composite another game's picture | reshade.me |
Launchers and mod managers
- Mod Organizer 2 and Vortex manage Bethesda game mods (Skyrim, Fallout) without touching your game folder.
- Gale, r2modman and Thunderstore Mod Manager do the same for many Unity games, Valheim included.
- Prism Launcher manages Minecraft instances. SkyCraft, ValCraft and others ship a portable copy, so you don't install anything by hand.
How to read a project's requirements
Requirements usually look like "Minecraft 26.3, Fabric Loader 0.19.5+, Fabric API, Java 25". In plain words:
- Game version: must match exactly unless it says "or newer".
- Loader version: "0.19.5+" means that version or newer.
- Libraries (Fabric API, Address Library): other mods the mod depends on. Install them too.
- Runtime (Java 25, .NET, Visual C++ Redistributable): software your PC needs. Launchers like Prism download Java for you.
Special cases
- GTA V comes in Legacy and Enhanced editions. Most passthrough projects target Legacy, and ScriptHookV refuses to run in GTA Online.
- Elden Ring mods load through ModEngine 2 and only work offline with Easy Anti-Cheat disabled. Never go online with mods.
- Rust rewrites (IW4L, the Skate 3 engine) and recomps don't use loaders at all: they're their own programs that read your game files.