Base NPC Swapper

Dynamically (F4SE) replace any NPC in the game at runtime using INI files. No leveled list conflicts, no (hopefully) broken quests.

One DLL now covers all three Fallout 4 builds: OG (the original pre-Next-Gen 1. 10. 163), NG, and AE. AE is the version this mod is developed on. OG is now tested too - the full 60-test suite was run on 1. 10. 163 and every check that load order could exercise passed. NG support is still EXPERIMENTAL: believed correct, but nobody has confirmed it in-game yet. If you run NG, please test and report back; that is exactly the feedback needed to call it supported. You still need the Address Library entry matching your exact exe version.

Needs F4SE, Address Library, and optionally Hydra if your rules use EditorIDs (highly recommended).

Github page.

⚠️ BETA STATUS WARNING ⚠️

This is a BETA release of a highly complex engine-level plugin. Might break a quest! If so, report a bug.

This started out as a pure swapper, but it's now a full filter and modification system that can replace, spawn a bodyguard, or modify actors dynamically, with more features incoming.

The Problem with Fallout 4 Leveled Lists

If you've spent any time modding Fallout 4, you know that adding new enemies to the game is a nightmare. Unlike weapons, NPC leveled lists are an absolute tangled web of inheritance. If a mod author tries to dynamically inject a custom "Super Mutant War Machine", there is a high chance it will break a template or cause naked enemies to appear.

Because of this, mod authors usually bypass leveled lists entirely and place their custom enemies by hand. Take RascalArt's incredible Locked and Loaded mod. It adds some amazing Gunner robots. But because they are hand-placed, you will only see them where the author put them. When Gunners attack your settlement, those robots won't be there.

The Solution

BaseNPCSwapper (BNS) is an F4SE plugin that intercepts the Creation Engine right as an NPC is loading their 3D skeleton. Before they even render on your screen, BNS reads your INI rules and seamlessly swaps their DNA, spawns an ally next to them, or injects items into their inventory.

Want to see RascalArt's robots during settlement attacks? Just write a simple INI rule telling BNS: "Whenever the game spawns a Gunner leveled 40-70, there is a 5% chance to spawn a Locked and Loaded Heavy Assaultron alongside them".

Features & Safety (How it works)

Replacing actors in Bethesda's engine is pretty dangerous. We took great pains to engineer this plugin to be as safe and robust as possible:

[]Uniques & Essentials are safe: BNS automatically ignores any NPC marked as Unique or Essential by default (though you can override this in the INI).[/]

[*]Quest Integrity (In-Place