---
title: "Passthrough modding"
description: "Passthrough modding is modding through the games you already own, and their mods too: mount your own copy in place, convert it as it loads and build on top, with no game content ever extracted or shipped."
url: "https://evil-engine.com/passthrough-modding"
modified: "2026-11-01T05:02:56.000Z"
---

# Passthrough modding

Mod the games you own through your own copies, never around them.

## What it is:

Passthrough modding is modding through the games you already own instead of around them.

Nothing gets extracted, ported or redistributed. Each player points Evil Engine at their own copy, it reads the files right where they sit, converts them as they load, and mods build on the converted result.

The game's content only ever passes through: from your copy, through the converter, into your session.

## How it works:

1. ### Mounts  
Every file reads straight from your own copy.  
Point Evil Engine at an install folder, a workshop folder or a disc image. Every file reads right where it sits. Nothing gets extracted or copied out.
2. ### Converts  
Its content becomes Evil Engine content.  
Each engine's formats convert into Evil Engine's own open formats as they load. Models, textures and materials first, maps after.
3. ### Plays  
Its stuff spawns and runs in game.  
Converted content spawns into one shared sandbox, side by side with every other game you've mounted, and Plugins build on top of it.

## Mod modding:

Mods are content too.

A mounted game's own mods and workshop items mount right along with it, each as its own layer you can turn on or off without touching the game's files.

That makes them content like anything else. Once Plugins run, they build on a game's mods the same way they build on the game, so the mods themselves get modded.

## How it compares:

__Classic mods, asset ports and passthrough modding, compared__
|                                     | Classic mods                  | Asset ports                      | Passthrough modding                     |
| ----------------------------------- | ----------------------------- | -------------------------------- | --------------------------------------- |
| Where the game's content comes from | The game the mod was made for | Copied out of another game       | Each player's own copy, read in place   |
| Ships another game's content        | No                            | Yes                              | Never                                   |
| Games in one session                | One                           | One, plus whatever was copied in | Any you've mounted                      |
| A game's own mods                   | Run in that game only         | Left behind                      | Mount alongside it, each one toggleable |

## FAQ:

### What is passthrough modding?

Modding through the games you already own instead of around them. The engine mounts each player's own copy in place, converts its content as it loads, and mods build on the converted result. No game content is ever extracted or redistributed.

### Why "passthrough"?

A game's content only ever passes through: read from your copy, converted as it loads, and used in your session. It's never copied out, stored or sent to anyone else.

### What is mod modding?

A mounted game's own mods and workshop items mount right along with it, each as its own layer you can turn on or off. They're content like anything else, so Plugins can build on them and the mods themselves get modded.

### Do I need to own the games?

Yes. Every player mounts their own copy. A Plugin that needs a game requires every player in the session to have it mounted, and copies are checked against each other without sending any game content.

### Is it the same as asset ripping or porting?

No. A port copies content out of one game and ships it inside another. Passthrough modding never copies or ships anything: it reads each player's own copy while they play.

### Can I use it with no games mounted?

Yes. The engine runs with nothing mounted, and content made from scratch in its open formats is first-class, not a fallback.

### Which engines does Evil Engine mount?

It learns engines, not games, so every game on an engine reads through the same code. So far: Source, Unity, EA Pegasus, HPL3, Phoenix, BeamNG, Quake, Blitz3D and Unreal Engine.

## In short:

- **Mount**: A game, a platform and a build, read in place from your own copy.
- **Convert**: Turning a mounted game's formats into Evil Engine's open ones as they load.
- **Plugin**: Evil Engine's own mod format, shaped around Lua. It can require mounts.
- **Mod modding**: Building on a mounted game's own mods, which mount right along with it.

## Engines so far:

- [Source](https://evil-engine.com/#home-engines): Reads VPK and GMA archives, MDL models, VTF textures and VMT materials
- [Unity](https://evil-engine.com/#home-engines): Reads UnityFS bundles, Addressables catalogs and serialized files
- [EA Pegasus](https://evil-engine.com/#home-engines): Reads BIG archives and Attrib vaults
- [HPL3](https://evil-engine.com/#home-engines): Reads loose resource folders, XML maps, entities and materials, and entry.hpc mods
- [Phoenix](https://evil-engine.com/#home-engines): Reads loose Data folders under the game's own core mods, baked DDS and model caches, and XML read the way TinyXML reads it
- [BeamNG](https://evil-engine.com/#home-engines): Reads ZIP archives laid over the game's own folder, .link redirects, textures named as PNG and shipped as DDS, and jbeam vehicles whose meshes and materials are found by name
- [Quake](https://evil-engine.com/#home-engines): Reads PAK archives, each laid at the game folder it belongs to
- [Blitz3D](https://evil-engine.com/#home-engines): Reads loose files found by path, RMesh rooms that name what they draw, and mods whose INI tables merge into the game's
- [Unreal Engine](https://evil-engine.com/#home-engines): Reads paks and IoStore containers, every file named without unpacking a byte, and the record of what each package loads

## Read the devlogs:

- [Proving the promises](https://evil-engine.com/devlogs/proving-the-promises)
- [Starting over on purpose](https://evil-engine.com/devlogs/starting-over-on-purpose)
- [Garry's Mod's materials, matched](https://evil-engine.com/devlogs/every-material-matches)

## Stay up-to-date

- [RSS](https://evil-engine.com/rss.xml)
- Mailing list
- [Steam](https://store.steampowered.com/app/3731310/Evil_Engine)

[Wishlist Evil Engine](https://store.steampowered.com/app/3731310/Evil_Engine)