Asset editing

As you know, Unreal Engine source is freely available, meaning that anyone can look at the code to see how certain systems work to try and reverse them. This is precisely what happened with the various cooked asset formats (.uexp, .uasset, .ucas, .utoc, .umap etc.) and several tools have been developed to make exploring, parsing, and editing these files as easy as possible.

The most basic form of asset editing is just changing the default values of primitive variable types like strings, floats and booleans. It can be done on every engine version by all asset editing tools. A typical use case would be changing the damage of a weapon.

The next level up from that is changing references to classes and objects, for example switching a component on an actor from one asset to another. Asset editing can go much further with super advanced techniques, but you get the point.

There is also localization editing, where the localisation files, that have the extension .locres, are edited, since that is usually where many of the games’ strings are kept. This is handled by a separate tool.

Asset editing is the most accessible method as many tools and documentation exist for it, but it is also quite limited and has big downsides:

• If the game updates the asset, it is very likely that the edit will be impacted due to the offset changing
• This method requires replacing the entire asset, which makes conflicting with other mods or even the game itself much more likely - even if the mod is changing one value out of hundreds in the asset.