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Eidos

The native Linux mod manager that never touches your game.

Eidos gives Bethesda games on Linux what Mod Organizer 2 gives them on Windows - a virtual, per-launch merged view of your mods - built from Linux primitives instead of Windows API hooking. No Wine for the manager. No files copied into the game directory. No cleanup path, because there is nothing to clean up.

Steam ──> eidos-gui %command% ──> [ private namespace ]
                                  │  mods ⊕ game  ──> what the game sees
                                  └─ dies with the game; the install stays pristine

Status: Skyrim SE is played through Eidos daily - SKSE, script-extender preloaders, Creation Club, LOOT-sorted load orders, per-profile saves, the lot. One game family proven in real play so far; ten more are wired and waiting for testers.

Why Eidos

  • 🔒 A mount only your game can see. The merged view lives in a private mount namespace: your file manager, your backup job, a second game - none of them see it, none of them need permission for it. Kill the game, pull the power: the namespace dies with the process tree and your install is exactly as it was. There is no residue by construction.
  • 🧾 One copy of the truth. Your profile owns its mod list, plugin order, INIs and saves. The plugin files and the save directory are bind-mounted over the game's own paths at launch, so even the game's own writes land in your profile. Switching profiles switches everything.
  • 🐧 Fully rootless. No setuid helper, no daemon, no sudo setcap, no /etc/fuse.conf edits. One binary, one Steam launch option.
  • 🛡️ Guards with receipts. A crash that wrecks your plugin list is flagged against a pre-session snapshot, with a one-click restore. A capture that would wipe your load order is refused and says why.

What it does

Mods. Simple archives, FOMOD wizards, Wrye Bash BAIN packages, a manual picker for the rest - and root mods natively (script extender preloaders, ENB, Engine Fixes), with no Root Builder plugin and nothing copied into your install. Hide single files, group with separators, targeted moves, per-mod notes and categories, and an MO2 profile importer.

The list is MO2's, with its habits: eight optional columns and a sort on any of them, grouping by category or by source, double-click gestures, type-to-jump, per-mod backups that are inert until you restore them, and advisory flags for a mod whose layout this game will not load or that was downloaded for another one. Its file tree does the ordinary operations - new folder, rename, delete, open - and previews images and text without launching anything.

Plugins. The load order with LOOT sorting built in, mod indexes like the game computes them, missing-master warnings, and your DLC and Creation Club content shown as the unmanaged rows they are.

Instances. Global - managed centrally under ~/.local/share/eidos - or portable: a self-contained folder anywhere you want (a second drive, a games partition), movable and isolated, like MO2's. Portable instances are remembered across sessions; the GUI, the Steam launch and every CLI command follow the one you last used, and any command takes the folder wherever it takes a game id. Details in usage.md.

Profiles. Per-profile mod order, plugin state, INIs and saves. Saves are parsed, diffed against your current plugins - with a button that enables what a save needs - and synced back for Steam Cloud after every session.

Nexus. Connect an account and the site's "Mod Manager Download" button lands straight in your instance, with update checks against what you have installed, who made each mod and a link to their profile. A collection link lists its members joined against your instance - installed, downloaded, missing - which is reading a collection rather than installing one, and the pane says why. The Downloads tab is an archive library: filter, sort, hide without deleting, and purge the ones already installed. An offline switch stops all of it.

Tools. xEdit, BodySlide, DynDOLOD and friends run through the merged view inside the game's Proton prefix - they see your mods, their output lands in Overwrite, and one click turns it into a real mod. Whatever runtime each one needs is fetched on request, so a missing DLL is a button rather than an afternoon. xEdit and its QuickAutoClean twin are found for you - in the game folder, inside a mod, or in the tools directory you keep beside your games - with the right runtimes already chosen. Pin the ones you use, hide the ones you do not, give a tool its own Steam AppID when it is its own Steam app, and write a .desktop shortcut that launches it through the merged view without opening Eidos at all.

Diagnostics. Missing masters, orphaned archives, mod-list drift, damaged plugin sets - and, after a run, what the script extender's own log says actually loaded.

Where it keeps its own files. ~/.config/Colony/Eidos/ for what you chose - preferences, your Nexus session, your instance list, the game and add-on definitions you wrote - with logs under ~/.local/state/Colony/Eidos/. The layout every program in the Colony family uses. An older Eidos kept these in ~/.config/eidos/; the first launch after upgrading copies them across, says so in the log, and leaves the old directory exactly as it was.

How it compares

Eidos MO2 via Wine Fluorine-Manager Limo / link deployers
Manager runs natively ❌ Windows app in Wine ✅ (Qt port)
Game dir untouched ✅ always ❌ links written into it
Mount visible to the game only the game only the whole system n/a
Crash cleanup needed none, by design none stale-mount recovery manual un-deploy
Root mods (ENB, preloaders) ✅ native plugin required plugin required partial
Privileges required none none /etc/fuse.conf edit none

How fast it is

before now
loading a save ~20 seconds 6-7 seconds
directory reads in one session 5.6 million 465 thousand

Cell changes are immediate. The gain came from asking your mods fewer questions: finding one file used to interrogate all fifty of them in turn, and listing one folder used to do it fifty times over. Neither does any more. Measured on a real instance played normally, not on a benchmark.

Get started

git clone https://github.com/Project-Colony/Eidos && cd Eidos
cargo build --release
install -m755 target/release/eidos target/release/eidos-gui ~/.local/bin/

Then set your game's Steam launch option to ~/.local/bin/eidos-gui %command% and press Play.

Arch packages and release tarballs, what you need installed first, and the CLI route: docs/guide/install.md.

Steam launch options

The base line is all most setups need:

~/.local/bin/eidos-gui %command%

Everything else is environment variables stacked in front of it, and they combine freely:

You want... Put in front
DLSS with Community Shaders PROTON_ENABLE_NVAPI=1 - without it DLSS silently never initialises; the full checklist is guide/graphics.md
an FPS counter on screen DXVK_HUD=fps
driver-level frame interpolation, zero mods (RTX 40/50) NVPRESENT_ENABLE_SMOOTH_MOTION=1 - never together with Community Shaders' own frame generation
verbose logs for a bug report EIDOS_LOG=debug (session logs land in ~/.local/state/Colony/Eidos/logs/)
a per-session I/O report from the mount EIDOS_FUSE_STATS=1
a different FUSE worker count EIDOS_FUSE_THREADS=8 (default 4; 1 is the first thing to try when chasing a concurrency bug)
this launch pinned to one portable instance EIDOS_INSTANCE=/path/to/folder - without it Eidos opens the instance you last used, which is usually what you want

The line to keep for a modern modded setup (Community Shaders, DLSS, frame generation) - this is the final command, not an example:

PROTON_ENABLE_NVAPI=1 ~/.local/bin/eidos-gui %command%

Add DXVK_HUD=fps in front while verifying the setup works, drop it once it does.

The deeper diagnostic switches (EIDOS_FUSE_TRACE, the cache and index bisection toggles, why EIDOS_FUSE_PASSTHROUGH is off by default) live in guide/troubleshooting.md.

Where to go next

If you want to...
install it guide/install.md
learn the CLI and the GUI guide/usage.md
set up xEdit, BodySlide or DynDOLOD guide/tools.md
play Fallout 4 (F4SE, versions, the NVIDIA debris crash) guide/fallout4.md
get DLSS / frame generation working (Community Shaders) guide/graphics.md
fix something that looks wrong guide/troubleshooting.md
know why it is fast, and check it yourself internals/performance.md
understand how it works inside internals/architecture.md
build it, test it, contribute internals/contributing.md
know why it exists at all project/landscape.md

The whole index is at docs/README.md; security policy and how to report a vulnerability at SECURITY.md.

Language

The pages a player needs are translated. English is canonical: when a translation disagrees with it, the English file is right.

Everything else is English on purpose, not by omission. docs/internals/ and docs/project/ are read by people who are also reading the Rust, and CHANGELOG.md is generated. Translating them would be 17,678 more words to keep honest for an audience that does not need them.

Each translation carries the hash of the English file it was made from, and CI fails when the English moves ahead - see scripts/i18n-check.sh. A translation that cannot be brought back up to date is deleted, not left in place: a stale page still looks authoritative and hands out last month's commands, which is worse for the reader than being sent to English.

A language is one directory. docs/i18n/<lang>/ mirrors the repo root, so docs/i18n/de/docs/guide/install.md is the German docs/guide/install.md - which is what makes a link between two translated pages the SAME string as the link between their English originals, and what makes retiring a language one rm -r.

Supported games

Skyrim SE/AE - proven in real play. Fallout 4 is wired end to end too (F4SE swapped in automatically, archive invalidation, asterisk load order, LOOT, .fos saves) - see guide/fallout4.md. Wired per the shared game descriptor and looking for testers: Skyrim LE, Skyrim VR, Enderal SE, Fallout 3, Fallout NV, Fallout 4 (+ VR), Starfield, Oblivion and Morrowind (the last two mount and manage mods; their timestamp-ordered plugin lists are not managed yet).

Adding a family is one descriptor row: internals/adding-games.md.

Prior art and thanks

  • ModOrganizer2 and usvfs - the semantics Eidos reproduces, and the codebase its parity was studied against
  • LOOT - the sorting engine, via libloot
  • Fluorine-Manager, Limo and the other Linux managers - proof there is a community that wants this solved

License

GPL-3.0-or-later. Mod management belongs to everyone.

About

A native Linux virtual filesystem for game mods: a from-scratch MO2/usvfs alternative built on FUSE + namespaces, no Wine-shoehorning.

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