Ooh overlayfs is quite interesting. I'll have to take a closer look at that. I imagine it's similar to what MO2 was doing on windows with the virtual filesytem to keep the game directory clean.

The stow approach is something that I considered but ultimately rejected for a couple of reasons around handling conflicts of game-installed files as well as how to ultimately handle the symlink lifecycle (eg wrapper to make the "non-running" state always clean or to let it always persist and then need to run manual cleanup/update steps). But if you're interested in that approach when I was applying for Nexus Mods approval I discovered https://github.com/Marc1326/Anvil-Organizer in the overall list of mod tools which I believe uses that strategy (though I haven't really looked too closely)

But basically my original idea to just install the files directly into the game directory stems from the fact that when I switched to linux for gaming and not having success with MO2 that's literally what I was doing. I would download the mod from nexus and unzip/tar it into the game directory manually. When I wanted to uninstall or update I'd find the original archive list the files in it and then delete them from my game directory. After doing this too much I realized that I was basically missing the functionality of a standard linux package manager (eg apt, pacman, etc)

I've really only tested it with Cyberpunk 2077 (and a bit of WH40K rogue trader). The issues (so far) are with tangential features. For example it's possible to define rules when you extract files (eg the mod author sticks them in a subdirectory or something you can have the tool automatically strip that leading directory) the "preview" feature to see how to rules affect the files before extraction isn't working as expected. But the main loop of create a profile for the game, add/remove mods to it, and have it spit them out into your game directory works without issue.

I should add that it's a CLI tool only (I may add a TUI later but it probably won't ever have a GUI if that matters). Anyway if you check it out and have any feedback whether positive or negative that would be cool

That's a fair question! When I was on windows I never actually used Vortex, I only gave it a try on Linux when I had problems with MO2. But being an Electron app it's very unappealing to me. As for MO2, well, I don't really know C++ and wouldn't even know where to begin contributing even if I did... just for starters there's the whole question of how the virtual filesystem that MO2 does would work if it were native linux. In any case I know Go and wanted to implement some things that I didn't like how MO2 worked (eg tracking the version of additional mod files instead of just the main one). Plus new stuff like making a portable mod bundle that you can either backup or move to a new machine. Plus I generally like a CLI workflow :)

Vortex at one time did have a native Linux version. IIRC, it had very minimal game support, lagged behind the main branch, and was eventually canceled. I don't think they're interested in contributions for native Linux. A separate app seeking to implement Vortex API and package support would potentially be more free to improve the UX, do Flatpak/Appimage, or use more interesting Linux features like overlayfs and FUSE archive mounting. I have a mind to try my hand at it, would be a good starter project for a new language.

MO2 works fine on Linux! It’s a bit slow to start but I found it very usable, a bit less polished than Vortex maybe but it absolutely gets the job done and I got my head around it inside of an hour.