All GOG games work without Steam.

Some still try to connect to it though - and some dont work once they have.
Sadly dont have a comprehensive list

This behaviour might be associated with the steam dlls that are present on some GOG games.
If you have steam on your pc and play through galaxy, probably things get confused in the middle and steam dlls try to open steam.
Once they connect, Steam revalidates its dlls inside GOG game installation folder and makes it DRM'd again.

It works fine without any client (Steam or Galaxy).

But to stick to the one game in question: Yes, the GOG version of Skyrim runs without Steam.

Edit: Deeem Ninjaaas!

I dont use galaxy at all. Just pointing out a generic issue with "drm free" games (not just from gog).

Yes, obviously the steam.dll is the culprit - but even changing it doesnt always work.

The GOG version of The Town of Light always launches Steam VR of all things lol.

I mean it kinda makes sense, since it has VR support, but it should be a toggle or something in the settings, it gets a bit tedious having to manually exist Steam VR every time I launch this game.

Annoying behavior to be sure, but you're still telling me it works without Steam. I see no mention of VR/virtual reality on the store page, so it's not like anyone was tricked into expecting that. It's more of a bonus feature that's implemented in an irritating way.

What a load of crap. Its crap. What you said is crap.

No other way to frame it. Makes NO sense at all.

Yes, it does work without Steam, but it launches Steam VR every time you start the game. VR support is mentioned on the Steam store page. Maybe they didn't expect anyone from GOG to have VR and thus didn't test it, or bother mentioning it. Still though, Hellblade handled it better by having a separate VR game.

I view the question in the OP more broadly.

I'd say the GOG version of Skyrim has only ever partially worked, because it is not and never will be compatible with 100% of the mods that were made for the game, which is because GOG's customers became majorly and permanently shafted whenever GOG and/or Bethesda decided to give the GOG version a different patch number than the Steam version.

That decision condemned the GOG version to always & forever be inferior to and to lack tons of mod compatibility which the Steam version does have to a much large degree, and therefore the Steam version is much more fully working than the GOG version is or ever will be --- at until least if and when GOG and Bethesda ever decide finally to do the right thing, and give both versions an identical patch version number, which is exactly what they should have done starting on day one in order to ensure quality parity between both versions and 100% mod compatibility with the GOG Version.

But sadly, they will probably never do that (especially since most GOG customers give Bethesda and GOG a free pass for this crap), and so the GOG version will never be fully working IMO.

I am concerned with how GOG Skyrim works with mods. My current Skyrim build has hundreds of them, representing a very large time investment, one of the major reasons I'm furious with Steam for taking my game away from me. So I want to know if I can start again with GOG Skyrim, and ditch Steam forever. I am SO glad I only ever got the one game from them. Hearing about the different version numbers is upsetting, though.

There's other software too that uses Steam VR without using the Steam Client itself and I find it quite annoying.

But when VR is turned off, it really should not launch SteamVR, that much is true.

GOG has both the standard Special Edition and the Anniversary Update with all their advantages/disadvantages when it comes to mods.

Different build numbers don't mean anything. Version differences ... more important than the number is to know, what was changed.
A version update can have been system specific, for example adding achievement support for GOG. In that case the dev could alter the number and Steam-Players would complain about having a lower number.

I'm running the GOG version just fine with SKSE, SkyUI, etc, and most other Nexus mods. Skyrim (GOG) has a different GOG version precisely because it's a different build (no DRM'd Creation Club). The "my mods don't work" issue Ancient-Red-Dragon has it that some Mod Packs (where 1,000 mods are pre-packaged into one) don't work because they were hard-coded to specific Steam versions - but that's the fault of the Mod Pack creator as Steam has also broken compatibility with same mod packs before when the game was upgraded over there. Mod Packs are also notoriously flaky in that one upgraded mod can break another but since they're all bundled together it's 1000x harder to troubleshoot.

As described previously, the SKSE for the GOG version was available virtually from day 1. The biggest difference you need to be aware of is the cause of "Nexus Vortex didn't install them properly" was that the GOG version uses a different folder name:-

Config & Save Location:-

Steam : %USERPROFILE%\Documents\My Games\Skyrim Special Edition

changed to...

GOG : %USERPROFILE%\Documents\My Games\Skyrim Special Edition GOG

And for the Mod Load File (plugins.txt) Location:-

Steam : %USERPROFILE%\AppData\Local\Skyrim Special Edition

changed to...

GOG : %USERPROFILE%\AppData\Local\Skyrim Special Edition GOG

ie, the fix for things like Nexus Vortex not 'seeing' the GOG mods (which may have since been updated anyway) was just to copy the files from the Steam to the GOG location (same name with " GOG" suffix). If you're installing mods manually (as I do) there never really was any issue and both the game and most mods work fine, installed 100% offline with zero client or Internet connection.