collections2mo2

Nexus Mods collections as portable Mod Organizer 2 instances, without Vortex, in one command or one guided GUI wizard - and optionally export the finished instance as a .wabbajack modlist for others to install.

collections2mo2 (c2mo2) downloads a collection's manifest, downloads every mod it references, replays the curator's recorded FOMOD choices, applies the curator's mod order and rules, merges the collection's INI tweaks, and lays it all down as a self-contained, portable MO2 instance - with the game copied into a Stock Game folder so nothing a collection does can ever touch your real Steam install.

Screenshots

Home	Collection

Progress	Manage

How it works

1. Fetch - download the collection's manifest (collection.json) from Nexus Mods.
2. Download - fetch every mod archive the manifest references, MD5-verified, using your Nexus Premium key.
3. Inspect - open each archive to find FOMOD installers and work out its layout.
4. Install - build every mod's folder: replay the curator's recorded FOMOD answers, apply exact file lists for "replicate"-mode mods, and route game-root files (SKSE, DLL shims, engine patches) through Root Builder.
5. Profile - order mods by phase and the curator's rules, write modlist.txt/plugins.txt/loadorder.txt, and merge in the collection's INI tweaks plus your resolution/vsync/window choice.
6. Build - lay down a portable Mod Organizer 2 + Root Builder, copy the game into Stock Game, and point MO2 at the copy.

From there you can install optional tools (xEdit, LOOT, DynDOLOD, ...), layer more collections on top, update a layer to a newer revision, or export the finished instance to a .wabbajack modlist.

Every stage is resumable. A stage is skipped when its output is already on disk and consistent with the stage before it, and the download stage checks each archive against the manifest's MD5 rather than trusting the file name. So if a run stops part way (a dropped connection, a stage that failed, closing the app) just run the same create again on the same folder: in the GUI pick the same instance folder, on the CLI repeat the command. A 60 GB collection that got as far as inspecting picks up at inspect without downloading a single archive again. --reuse-downloads <folder> seeds a new instance from another instance's download store the same way, by hardlinking the archives that match.

Requirements

• Windows 10 or 11.
• A Nexus Mods account with a personal API key (Account Settings -> API Access). Nexus Premium is required for automatic downloads - the API only issues direct download links to Premium accounts. A free account can still fetch a collection's manifest and browse it.
• A Steam copy of the game the collection targets. Tested end-to-end on Skyrim Special Edition; other Bethesda games (Skyrim, SkyrimVR, Fallout 4, Fallout New Vegas, Fallout 3, Oblivion) are mapped but not verified.
• Free disk space: roughly the collection's download size, plus the same again for the extracted mods, plus about 20 GB for the Stock Game copy.
• Wabbajack only if you want to export a .wabbajack
  • c2mo2 wabbajack will download wabbajack-cli itself if it isn't already installed.
• A short install path (e.g. D:\GTS, not C:\Users\...\Documents\My Modding Projects\...) - and not under Program Files, Documents, Desktop, OneDrive or a Steam library. The wizard and create warn about all of these.

The packaged .exe on the releases page is not code-signed yet, so Windows SmartScreen shows "Windows protected your PC" on first launch (More info -> Run anyway), and Windows Defender has flagged some builds as a virus. That is a false positive; see Windows says the download is a virus for why, how to verify the file, and how to run from source instead.

Quick start: GUI

uv sync
uv run c2mo2-gui

The wizard: paste your Nexus API key (stored in Windows Credential Manager, never sent anywhere but Nexus) -> paste a collection URL -> pick an install folder and your game folder (Steam installs are auto-detected) -> pick optional tools -> pick display settings -> review -> Start. The Manage tab (from the home screen) reopens an instance you already built: add or remove a collection layer, update a layer, install more tools, or export to Wabbajack. Removing the base collection is CLI-only (c2mo2 remove <slug> --force); the Manage tab offers "Remove instance...", which deletes the whole instance folder, instead.

Quick start: CLI

uv sync
cp .env.example .env      # paste your personal Nexus API key into .env

# Build a complete instance in one step
uv run c2mo2 create https://www.nexusmods.com/games/skyrimspecialedition/collections/h2uqa3 \
    --out "D:/h2uqa3" --game-path "D:/SteamLibrary/steamapps/common/Skyrim Special Edition" \
    --stock-game

# Install optional modding tools
uv run c2mo2 tools install xedit bethini-pie loot --mo2-dir "D:/h2uqa3"

# Layer an add-on collection on top
uv run c2mo2 add https://www.nexusmods.com/games/skyrimspecialedition/collections/xk05aw \
    --instance "D:/h2uqa3"

# Move a layer to its latest published revision (only the delta is re-downloaded)
uv run c2mo2 update --instance "D:/h2uqa3" --yes

# Export to a .wabbajack modlist
uv run c2mo2 wabbajack --instance "D:/h2uqa3"

See docs/cli.md for every subcommand and option.

Verified

Built and confirmed working end to end on:

• SKSE and Behaviours Essentials (292 mods) - builds, opens clean in MO2 2.5.2, every plugin in the curator's load order present.
• Gate to Sovngarde V117 (1,966 mods, 58.6 GB) - builds, opens clean in MO2 2.5.2, launches through SKSE, every plugin in the curator's load order is present, and the exported .wabbajack (809 KB) installs cleanly with Wabbajack 4.2.2.1.

Terms and etiquette

• Converting a collection for your own use is fine.
• Publishing a compiled .wabbajack of someone else's collection requires that curator's permission. Community conversions of Gate to Sovngarde, for example, obtained it first - do the same.
• c2mo2 identifies itself to Nexus Mods with its own User-Agent, honours Nexus's rate limits, and only ever downloads with your own Premium key - it does not proxy, cache, or redistribute anyone's files.
• Whatever you build is yours to use. The collection's content - the mods themselves - still belongs to their authors and to the curator who assembled the list; this tool just automates the install.

FAQ

Full answers in docs/faq.md. Short version:

• My resolution/vsync setting was ignored. Some collections ship SSE Display Tweaks, which overrides SkyrimPrefs.ini entirely. Set it in the wizard, or c2mo2 profile-instance --resolution WxH.
• MO2 shows SkyrimRuntimeSwapper.exe when I launch SKSE. By design on collections that need a specific game version - it downgrades at launch and reverts on exit.
• Which Skyrim version does it need? Whatever the collection was built against. It never changes your game: with Stock Game it works on a copy, so you can downgrade or patch that copy freely, and Steam's install stays untouched. The wizard and create warn when your game's version differs from the collection's.
• First MO2 start takes a minute or more. It's indexing a couple thousand mods. Normal.
• The game says DynDOLOD's scripts are the wrong version. The collection ships its own DynDOLOD Resources/DLL NG and an older c2mo2 installed newer copies above them. Install the DynDOLOD tool again and it removes its copies (see docs/faq.md).
• xEdit/DynDOLOD only see vanilla plugins. Run c2mo2 tools refresh on instances built before this was fixed.
• "Path too long" errors. Install to a short path.
• "A required patch is missing" from the Runtime Swapper. Your Stock Game copy isn't the exact game version the collection expects.
• I'm not Premium - now what? Automatic downloads won't work yet; manual-download support isn't implemented.
• Can I add my own mods? Yes - they keep their position across update/add/ remove.
• A FOMOD mod took the installer's defaults. "Fresh install" mods (no recorded choices) do that by design, and it's called out in the run's log.
• Where's my API key stored? Windows Credential Manager for the GUI, .env for the CLI. Never printed, never committed.

Status and limitations

• Windows only.
• Nexus Premium required for automatic downloads; manual-download mode isn't implemented.
• Vortex "replicate"-mode patches (binary diffs against an existing file) aren't implemented - collections that use them will warn, not fail.
• Verified end to end on Skyrim Special Edition only. Other Bethesda games are mapped in the code but untested.
• No signed release binary yet - run from source with uv.

Licence

GPL-3.0-or-later. Not affiliated with Nexus Mods, Mod Organizer 2, Wabbajack, or any collection curator. Third-party software this project bundles or downloads at run time is listed in NOTICES.md.

Credits

• Mod Organizer 2 and Root Builder by Kezyma
• Wabbajack
• 7-Zip
• The xEdit team
• DynDOLOD by sheson
• The Nexus Mods collections and modding community
• Inspired by Furglitch's MO2 nxm-collection-dl plugin, the starting point for this project's investigation into converting collections outside Vortex

For development docs (architecture, tests, linting, the work/ layout), see docs/development.md and docs/architecture.md. See CONTRIBUTING.md for how to get set up and submit a change, and CHANGELOG.md for what's new in each release.