A complete pipeline for converting Morrowind, Oblivion, Fallout 3 and Fallout: New Vegas into Skyrim Special Edition: records, meshes, textures, collision, animations, sounds, dialogue, and scripts.

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This project is pre-alpha. Expect issues. Conversions are incomplete, and some features are only half implemented. Bugs are common across every stage, and output can change or break between releases. Updates will likely break your saves from converted games, so expect to start a new game after updating. Back up your saves before installing converted content.

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Important

No Bethesda assets are included in this repository. This project ships only code. It reads the game data you already own, on your own machine, and performs every conversion locally. Do not redistribute converted Bethesda assets. If you want the converted mod, download this project and run it against your own legally-owned copies of the games.

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What it does

This is a full data-conversion pipeline. It takes an .esm/.esp (plus its BSA or loose file assets) and produces a working Skyrim mod. Plugin, meshes, animations, everything. Ready to drop into your Data folder. It's in early alpha with a long bug list, but every part of the conversion is handled in one package.

Which games

Four source games are supported: Morrowind, Oblivion, Fallout 3 and Fallout: New Vegas. Total conversions such as Nehrim and Arktwend are also supported.

Morrowind is the odd one out and has its own section below.

• Record conversion — Every record type is remapped to its Skyrim equivalent, with all the structural fixups Skyrim requires and the companion records it expects alongside them.
• Creatures — Creature records become real Skyrim actors: skeletons and skinned meshes are ported, animations are recompiled to Havok .hkx, and, since the source games have no equivalent, a full Havok behavior graph is generated from scratch per creature (locomotion state machine, ragdoll, attack events, foot IK) based on the original data instead of reusing a donor from Skyrim. There are still a lot of bugs here.
• Mesh conversion — Source NIFs → Skyrim NIFs (v20.2.0.7): NiTriStrips→NiTriShape, shader system upgrade, texture path rewriting, bone remapping, and root-node conversion. Only a handful of meshes are currently unsupported or buggy.
• Havok collision — Full rigid-body, constraint, and mesh-collision conversion with real MOPP generation via a bundled Havok bridge. No crash-prone collision like the original Skyblivion generator.
• Skeleton retargeting — Armor and clothing meshes are re-posed from the source skeleton onto the Skyrim skeleton using an animation-corpus + optimization solver. Weapons, armor, and clothing (including pants/greaves) are fully functional and wearable alongside your existing Skyrim outfits without major clipping — a few meshes still clip slightly, and the torso/legs can currently go invisible when only one is equipped.
• Navmesh generation — Skyrim has no equivalent to the older games' pathgrids, so navmeshes are built from scratch: Collision is voxelized and triangulated per-cell into Skyrim NAVM/NAVI data using the original pathgrid as a guide so NPCs can actually path around the world. Could use a bit more refinement, but it mostly works well.
• Particles, fire & animated objects — Particle systems, flame nodes, flip-book fire, and keyframed collision are all converted to their Skyrim equivalents.
• SpeedTree conversion — .spt trees are procedurally rebuilt as Skyrim flora NIFs. The converter hooks directly into your Oblivion.exe so they are faithful replicas, but with leaves in an X shape instead of billboards.
• Dialogue & quests — Converted into Skyrim's branch/voice-type architecture, including voice-file renaming, topic/quest restructuring so NPCs greet and respond correctly, and barter/training menu hookup.
• Scripts — Source scripts are transpiled to Papyrus (.psc) source and compiled, which combined with the dialogue work means many quests are already playable.
• Guns (Fallout) — Guns get a purpose-built animation graph using faithfully converted animations.
• Sounds — Voice and sound files are converted (via ffmpeg + xWMAEncode), and lip-sync tracks are generated for every transcribed line using the Creation Kit's LipGenerator (voice ships as .fuz). Expect the occasional silent line.

In short, this project aims to be nothing less than a complete, faithful conversion of these games into Skyrim, and it's getting closer all the time. Contributions are very welcome, see TODO.txt for the current bug list and roadmap.

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Morrowind

Morrowind converts from its own files like any other game here, with two differences.

Dialogue runs natively. Morrowind's conversation system is a searchable topic list with its own filtering, journal and scripting language, none of which Skyrim can represent. Rather than flatten it and lose most of it, this project runs the real thing: a port of the OpenMW dialogue engine and script interpreter, shipped as a game plugin (MorrowindRuntime.dll) with a Morrowind-style menu. It is set up automatically.

Morroblivion mode. The converter can be made to use Morroblivion as a base instead of Morrowind so you can use all of its upgraded assets and worldspace.

Mode	Objects come from
Vanilla	Your own converted Morrowind.esm, Tribunal.esm and Bloodmoon.esm.
Morroblivion + patch	Morroblivion, the fan remake of Morrowind in Oblivion, converted through the normal Oblivion path.

Morroblivion mode needs a compatibility patch. Choosing Settings ▸ Morrowind source ▸ Morroblivion + patch builds it for you from your Morrowind Data Files if it doesn't exist yet (convert Morrowind_ob.esm first). If the patch already exists, it asks whether to rebuild it.

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Quick start

Setting up

1. Install the Skyrim Special Edition Creation Kit, free on Steam.
2. Install SKSE by copying its files straight into your Skyrim folder.
3. Install the Address Library for SKSE Plugins with your mod manager.
4. Download the converter: on the latest release, click Source code (zip), then unzip it somewhere like your Documents folder (not Program Files).
5. Double-click TES Auto-Convert.cmd in the unzipped folder.

The first time, it sets itself up. That needs internet and takes a few minutes, and it asks to download a free Microsoft tool used for voice lines; say yes. After that, double-clicking it just opens the converter.

You'll want a strong PC: it was tested with 32 GB of RAM, and converting Oblivion uses about 16 GB.

Converting

1. Convert a game. Your Oblivion install is found automatically; add Morrowind and Fallout installs with + under Source. Pick the game, leave the steps on Default, and click Run Selected Steps. If anything is missing, the converter tells you what to install.
2. Click each of these buttons once (click them again after converting another game or updating the converter):
   • Pack SKSE Mod: the converter's SKSE plugins. Converted games don't work without it.
   • Pack Start Mod: the new-game menu where you pick which world to start in.
   • Body Slot Patch: splits Skyrim's body into torso, legs and each hand, so converted armor pieces like greaves or a single gauntlet hide only the part they cover.
   • Create LOD, then Pack LOD: the distant view of the converted worlds.
3. Install everything in output/Finished Mods/ with your mod manager.
4. Start the game through SKSE (skse64_loader.exe, or your mod manager's SKSE button) and pick your world from the new-game menu.

Also in the converter:

• Build ▸ Quest Journal Stage Text makes a quest's objectives clickable in Skyrim's journal: clicking one shows the journal text the quest had when that objective appeared, and clicking it again returns to the current text. It works for every quest, converted or not. It patches whichever journal you run (vanilla, SkyUI or Quest Journal Overhaul) into output/Finished Mods/Quest Journal Stage Text.zip; install that after your UI mod. Needs MorrowindRuntime.dll, and covers objectives that appear after it is installed.

If you'd like to use modded source-game models or textures, run the Extract step first, then copy your modded files into export/<plugin name>/, overwriting what's there.

The Import step downloads a prebuilt navmesh cache automatically, which turns minutes of work into seconds. It only saves time and never changes the result. To skip the download, untick Settings ▸ Download navmesh cache. Offline, drop the release's .zip into navmesh_cache/.

Converting a downloaded mod

Drag a .zip / .7z / .rar onto the left panel, or use Plugins ▸ Import Mod Archive…, and it becomes a source like any folder in the list. Loose files, BSAs and nested archives are all handled; nothing is written to your game install. A mod with no plugin (a texture pack) imports too — the steps that need one are greyed out.

A copy of the archive is kept under export/<plugin>/_source/ so steps can be re-run after you delete the download. Plugins ▸ Manage Imported Mods… removes them. If a master has not been converted yet, the import says so.

What to install

Everything you install ends up in output/Finished Mods/. Install these with your mod manager:

• One .zip per converted game or mod, from Run Selected Steps
• TESRuntime.zip, from Pack SKSE Mod, required (see TESRuntime). It needs SKSE and the Address Library for SKSE Plugins installed, and the game launched through SKSE (skse64_loader.exe, or your mod manager's SKSE entry). Without them the runtime DLLs never load.
• TESGameSelect.zip, from Pack Start Mod: the new-game menu (see Starting a converted game)
• Body Slots Patch.zip, from Body Slot Patch
• AutoConvertLOD.zip, from Create LOD then Pack LOD: the distant view. Install it after the mods it covers.

The rest of output/ is working space. Don't install anything from it directly.

Upgrading

Paste a new download over your existing folder. The Upgrade button ticks only the steps that changed since your last conversion. If you're already current it says Up to date. If it can't tell, it selects every step.

Starting a converted game

The intended way in is the TESGameSelect plugin (Threads of Prophecy), a small standalone Skyrim SE plugin built separately from the conversion itself. It takes over Skyrim's opening quest so that starting a new game shows a menu asking which world to begin in: Skyrim, Cyrodiil, Vvardenfell, Nehrim, the Mojave or Morrowind. Choosing Skyrim runs the vanilla Helgen opening untouched; choosing a converted game hands off to that game's own character generation, with its real starting equipment and start location. Games whose plugin is not in your load order are detected at runtime and simply never appear in the menu, so any subset works.

Build it with the Pack Start Mod button (or python tools/release/package_start_mod.py) to get output/Finished Mods/TESGameSelect.zip, then install it like any other converted mod and enable TESGameSelect.esp. Because it overrides MQ101, it conflicts with other alternate-start mods (Live Another Life, Skyrim Unbound, Alternate Perspective) — use one at a time. See TESGameSelect/README.md for how it works, configuring it, and rebuilding.

Without the plugin, you can start a converted game from the console instead:

setstage Charactergen 5

or simply teleport to the worldspace with a command like

cow tes4tamriel 20 20

TESRuntime (SKSE plugin)

TESRuntime.zip holds the converter's own SKSE plugins, one DLL each. They need SKSE and the Address Library for SKSE Plugins; HavokWorldSize alone needs only SKSE.

• TESRuntime.dll, needed by every converted game: sends an arrested player to the nearest jail as the source games do, and lets a clicked quest objective show the journal text it came with.
• CreatureRuntime.dll: registers converted creatures' animations, so several mods can each add creatures without fighting over Skyrim's animation cache.
• FalloutRuntime.dll: the Fallout 3 / New Vegas gun handling Skyrim has no equivalent for.
• HavokWorldSize.dll (below).
• MorrowindRuntime.dll: runs Morrowind's dialogue and scripts.

Each logs to Documents\My Games\Skyrim Special Edition\SKSE\<name>.log. See tes_runtime/README.md for the details and for building them yourself. Build the zip with the Package SKSE Mod button, or python tools/release/package_runtime_dll.py.

HavokWorldSize

HavokWorldSize.dll stands on its own and is useful with any large worldspace. Skyrim's physics only works within 64 cells of the world center — past that, NPCs bounce in and out of the ground and you can't open doors or hit anything. Big worldspaces like Tamriel Rebuilt go well beyond that, so this widens the limit. Edit Data\SKSE\Plugins\HavokWorldSize.ini to change it (128 by default; use the smallest that fits your worldspace).

Changing the gun reload key

The reload key defaults to mouse button 4 and the iron-sight (zoom) key to right mouse. To change either, create Data\SKSE\Plugins\FalloutRuntime\FalloutRuntime.ini and give it a [Guns] section with the virtual-key code of the key you want, in decimal:

[Guns]
ReloadKey=82
ZoomKey=2

82 is 0x52, so that example moves reload onto the R key and leaves zoom on right mouse. The file is read once at startup, so restart the game after editing it. Omit a key, or the file entirely, to keep the default.

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Command line

Open a terminal in this folder and run .venv\Scripts\activate first, so python is the converter's own.

Run the full pipeline

python convert.py -f Oblivion.esm

With no --*-only flag, the default pipeline runs:

Export → Extract → Meshes → SpeedTrees → Creatures → Import → Sounds → Scripts

Run a single step

Each --*-only flag runs exactly that step and nothing else:

python convert.py -f Oblivion.esm --export-only        # Parse TES4 binary → text cache
python convert.py -f Oblivion.esm --import-only        # Build TES5 ESM/ESP from text cache
python convert.py -f Oblivion.esm --extract-only       # Extract assets from BSA archives
python convert.py -f Oblivion.esm --meshes-only        # Convert NIFs + copy textures
python convert.py -f Oblivion.esm --speedtrees-only    # Convert SpeedTree (.spt) files
python convert.py -f Oblivion.esm --creatures-only     # Convert creature models & animations
python convert.py -f Oblivion.esm --sounds-only        # Copy/convert sound files
python convert.py -f Oblivion.esm --scripts-only       # Transpile scripts → Papyrus
python convert.py -f Oblivion.esm --pack-only          # Pack output assets into Skyrim BSAs
python convert.py -f Oblivion.esm --pack-zip-only      # Zip plugin + BSAs → output/Finished Mods/
python convert.py --modify-body-meshes                 # Build ARMA slot-44 patch (takes no -f)
python tools/release/create_lod.py                             # Bake ALL LOD once (takes no -f)
python tools/release/pack_lod.py                               # Zip the baked LOD mod
python tools/release/package_start_mod.py                      # Zip the TESGameSelect starter mod
python convert.py -f Oblivion.esm --mesh-bounds-only   # Rescan mesh bounds → OBND cache

Common options

Flag	Description
-f, --files FILE…	Plugin(s) to process (default: all listed in the config)
--output-dir PATH	Output directory (default: output/)
--config PATH	Path to conversion_config.json
--mesh-subdirs SUB…	Limit mesh conversion to folders or single meshes under meshes/ (e.g. architecture dungeons/caves/triggers)
--skip-hair	Skip the hair baking pass after mesh conversion

Running individual tools directly

# Mesh conversion only
python -m asset_convert.nif.nif_converter path/to/meshes/ path/to/output/

# BSA extraction only
python -m asset_convert.sources.bsa_extract Oblivion.esm --data-path "C:/path/to/Oblivion/Data"

# Tests
python -m pytest tests/ -v

Development dependencies

Only needed to run the test suite — a conversion never uses these, so end users can skip this entirely.

Dependency	Purpose	Install
pytest	Test runner	pip install pytest

A few tools/ analysis scripts need extras nothing else does: pefile and capstone (exe disassembly), and pywin32 for game_bridge/test_protocol.py. Install those only if you run those scripts.

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Pipeline phases

These are the steps as presented (and run) by the GUI, in order:

#	Phase	What happens
1	Export	Parse the source binary into a per-record-type KEY=VALUE text cache (export/<name>/). A pure dump — no transformation.
2	Extract	Pull meshes, textures, and sounds out of the source game's BSA archives (cached via a manifest).
3	Meshes	Convert source NIFs → Skyrim NIFs and copy textures.
4	SpeedTrees	Procedurally rebuild .spt trees as Skyrim flora NIFs.
5	Creatures	Convert creature models and animations (skeletons, ragdolls, behavior graphs).
6	Import	Read the text cache and write the Skyrim binary ESM/ESP — all record transformations happen here.
7	Sounds	Convert voice files to XWM and copy sound files.
8	Scripts	Transpile source scripts to Papyrus and compile.
9	Pack BSAs	(opt-in, off by default) Pack the converted assets into Skyrim BSA archives.
10	Pack Mod Zip	Zip the plugin(s) and BSAs into a single archive for installation.

LOD is not in that list. LOD tiles sit on a fixed grid shared by every plugin that edits a worldspace, so baking them per plugin would generate each contested tile once per plugin and then throw all but one away. It is a Global action instead, baked once for the whole load order.

Some actions belong to no single plugin, so they are buttons under Global in the sidebar rather than numbered steps. Each runs once and covers everything you have converted:

Action	What happens
Create LOD	Generate all object and terrain LOD in one pass, into a standalone output/AutoConvertLOD/ mod. The button opens a panel choosing which plugins and worldspaces to include; the plugin order decides which one wins a contested tile (defaults to your plugins.txt order). Install it after the mods it covers.
Pack LOD	Zip output/AutoConvertLOD/ into output/Finished Mods/AutoConvertLOD.zip for installation.
Body Slot Patch	Build the ARMA slot-44 body patch for your whole Skyrim load order (select plugins... chooses which), as output/Finished Mods/Body Slots Patch.zip.
Start Mod	Zip the prebuilt TESGameSelect starter mod (see Starting a converted game) to output/Finished Mods/TESGameSelect.zip.
Package SKSE Mod	Zip the five runtime plugins (see TESRuntime) to output/Finished Mods/TESRuntime.zip.
Convert to Master	Flag converted plugins as masters. A non-master plugin has every reference treated as always-active, and the engine hangs on the main menu past about a million of them. Applies to a whole master chain at once.
Convert Oblivion UI	(Build menu) Build a standalone mod that reskins Skyrim's message boxes and cursor with Oblivion's artwork, read from your Oblivion install.

Design principle: the export is a pure dump of TES4 data — no type mapping, no path prefixing, no derived fields. All transformations live in the import and asset steps.

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Project structure

TESConversion/
├── convert.py            # Pipeline orchestrator (all phases, CLI)
├── gui.py                # GUI frontend
├── tes4_export/          # TES4 binary → KEY=VALUE text export
├── tes5_import/          # KEY=VALUE text → TES5 binary import (all record transforms)
├── asset_convert/        # Asset conversion pipeline
│   ├── nif_converter.py  #   NIF mesh conversion (strips, shaders, bones, collision, skin)
│   ├── collision.py      #   Havok collision conversion
│   ├── cms_builder.py    #   Compressed-mesh collision + MOPP generation
│   ├── skin_retarget.py  #   Source → Skyrim skeleton retargeting
│   ├── spt_converter.py  #   SpeedTree (.spt) → Skyrim flora NIF
│   ├── bsa_extract.py    #   BSA extraction with caching
│   └── asset_pipeline.py #   Extract → convert → output orchestrator
├── external/             # Third-party binaries & vendored code (see License below)
├── tools/                # Debug/analysis utilities (NIF/ESM dumpers, sanity checkers)
├── tests/                # Pytest suite
├── docs/                 # Format notes and reference docs
└── conversion_config.json

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Credits & License

First things first, I want to give credit to all the wonderful people I used to know on the Morroblivion forum, and those still working hard on Skyblivion and Skywind all these years later. You are an inspiration.

This project's own code is released under the MIT License. Everything under external/ is third-party and carries its own licensing — nothing in that folder is covered by this project's MIT license.

Contributor / Component	Used for	License / Terms
xEdit and all contributors	ESM record definitions; BSArch.exe (BSA packing) and LODGenx64.exe (object LOD) in external/	MPL-2.0 / GPL-2.0 (xEdit dual license) — redistributed
Zilav's Oblivion → Skyrim xEdit conversion scripts	The original inspiration and the information needed to get started	— (reference only, not redistributed)
NifSkope contributors	NIF format documentation	— (reference only, not redistributed)
Ormin — NIFConverter	Mesh conversion reference	— (reference only, not redistributed)
Ormin — ScriptConverter	OBScript → Papyrus transpilation reference	— (reference only, not redistributed)
russo-2025 — papyrus-compiler	Papyrus compiler, external/papyrus-compiler/papyrus.exe	MIT (© 2025 russo-2025) — redistributed; license text in external/papyrus-compiler/LICENSE
LvxMagick — DovahNifWorkbench	Mopp Bridge, external/mopp_bridge/dovah_hkp_mesh_mopp_bridge.exe	No stated license (Nexus-only, no public source). Statically links Havok — see the Havok note below
Bad Dog — PyNifly	Pure-Python Havok hk_2010 packfile reader + hkaSplineCompressedAnimation codec (vendored in external/pynifly_hkx/) — the heart of creature animation conversion	GPL-3.0 (vendored from PyNifly 27.4.0; local changes marked # TESConversion:) — see the GPL note below
OpenMW	The Morrowind dialogue engine and MWScript interpreter, vendored into external/openmw/ and linked into MorrowindRuntime.dll	GPL-3.0 — see the GPL note below. Vendored by tools/generators/vendor_openmw.py; license text in external/openmw/LICENSE
figment — hkxcmd	Havok packfile XML↔binary compiler, external/hkxcmd/hkxcmd.exe, used to build skeleton/behavior/animation .hkx	BSD-3-Clause for hkxcmd's own sources (© 2011; text in external/hkxcmd/LICENSE.TXT). Statically links Havok — see the Havok note below
Monitor221hz — HKX2-Enhanced-Library	Skyrim SE 64-bit Havok packfile ↔ XML, external/hkxconv/hkxconv.exe, used to patch the vanilla humanoid behavior graphs (hkxcmd cannot read 64-bit files). Forked from ret2end, in turn from katalash / krenyy; bundles BinaryReaderEx from JKAnderson — SoulsFormats	No stated license anywhere in that chain (no LICENSE file upstream) — community project, publicly distributed and freely forked; redistributed here on that basis. Full chain and rebuild steps in external/hkxconv/README.md
Microsoft DirectX SDK (June 2010)	external/xwmaencode/xWMAEncode.exe, xWMA voice compression	Microsoft — not redistributed; the launcher fetches it from Microsoft (see Quick start)
FFmpeg	external/ffmpeg/ffmpeg.exe, decoding MP3/WAV voice and sound files	LGPL v2.1 or later — redistributed; license text in external/ffmpeg/COPYING.LGPLv2.1. See the LGPL note below
Oblivion banner font (dafont)	Project banner	Free for personal use only, based on Bethesda's trademarked logo. Not bundled in this repo; the banner ships as pre-rendered vector outlines.

Note on GPL-3.0: external/pynifly_hkx/ (creature animation conversion, asset_convert/havok/hkx_anim.py) and external/openmw/ (linked into MorrowindRuntime.dll) are both GPL-3.0. If you redistribute a build that includes either, the GPL's terms apply to that distribution. MorrowindRuntime.dll is kept a separate DLL for this reason. TESRuntime.dll carries a line-for-line port of OpenMW's alchemy apparatus formula (tes_runtime/tes/alchemy.cpp), so it is GPL-3.0 as well.

Note on LGPL (FFmpeg): external/ffmpeg/ffmpeg.exe is built from unmodified FFmpeg 7.1.2 sources under LGPL v2.1, with no GPL components (--enable-gpl and --enable-version3 are both off). Because it is statically linked, LGPL §6 requires that recipients be able to relink it against a modified FFmpeg — satisfied by tools/generators/build_ffmpeg.py, which pins the exact upstream tarball and records every configure flag used to produce the shipped binary.

⚠️ Note on Havok

Two bundled binaries — hkxcmd.exe and dovah_hkp_mesh_mopp_bridge.exe — statically link the proprietary Havok SDK. Both embed the notice:

Copyright 1999-2011 Havok.com Inc. (and its Licensors). All Rights Reserved. See www.havok.com for details.

Neither author's license grants any rights to the Havok code inside. These two binaries are redistributed here as-is.