Modding 101

The Basics

Sims 4 Mods use exactly two file types, .package files and .ts4script files.

Most mods are made entirely using .package files, and will be the main focus of most tutorials. More advanced mods can use .ts4script files to use Python scripting, but this is often unneeded and won’t be discussed until later.

If mods use multiple files, they are distributed as .zip files, but should be unzipped when installing.

Package Files

Package files are a custom file type designed by Maxis that contains Resources. Because packages are nonstandard file types, they require programs like Sims 4 Editor or Sims 4 Studio to view and edit.

Package Viewer An example mod with a DDS image resource viewed in Sims 4 Editor.

Resources

A resource is just a file that Sims 4 understands. Resources include text, XML, images, 3D models, animations, audio, etc. A resource is defined using a Resource Key.

Resource Keys

A resource key is a unique identifier for a resource. It has 3 parts: type, group, and instance. You can see these fields in the earlier image, with

Resource keys are used to either define new resources, or overriding existing resources. Resource keys will be discussed more in depth in the next section.

Summary

How Mods Work

Sims 4 loads all .package and .ts4sscript files in the Sims 4 Mods folder
Package Files contain files called Resources, which are defined using Resources Keys
Resource Keys determine if a resource overrides an existing resource, or creates a new one.

Sims 4 Studio lets you edit many resources at once using the Studio view, or edit individual resources using the Warehouse view.

Sims 4 Editor currently only allows editing resources directly, similar to S4S’s Warehouse view.