I've bought the game on GOG, and I'm running it through Steam as a non-Steam game. The moment I first did, Steam populated my library with an extra entry for the Steamworks version of COTL and has been tracking my time played on it. While I'm ingame it even shows the STOP button as though I were playing the Steamworks version, but once out of game, the PLAY button is instead a PURCHASE button. It's reminiscent of when I refund a game from my library but haven't uninstalled it yet, with the obvious exception of continuing to track my playtime. That and there not being any files in the steamapps folder, so I don't know how on earth it's shown up in the first place.

The playtime is not reflected in my public profile, only on the page in my library. It also invites me to write a Steam review since I've played for 4 hours... although it says 6 hours on the library page... and when I try to submit a review it errors out because I have 0 minutes on record. It's all truly bizarre to witness in action.

Considering the fact that games "from" Steam's shop are supposed to have a specific *.exe to be considered Steam-game, I think this may be more a bug from Steam than from te game, and even more anything to do about GoG.
And I highly doubt Steam will do anything about this, they would gain zero benefit fixing anything related to another platform than theirs. (I use steam since before it was a shop, and they always have pretty egocentric and profit motivated politics)

Conversely, I would say that considering there needs to be something very specific in the game for Steam to detect it as a Steamworks game, it's far likelier something that is in both the Steam and GOG release of the game that they neglected to properly "pave over", so to speak, for the GOG release. Such as, for example, the steam_api64.dll still being present in the "Cult of the Lamb\Cult of the Lamb_Data\Plugins\x86_64" directory.

It definitely doesn't act like family sharing tracking, at least. It won't unlock achievements, and the entry only exists on your local machine and only for the current session. It's not possible to even try to submit a review on a different computer as the entry isn't there. I'm surprised the playtime sticks when restarting Steam, I suppose there's a local cache that would get synced to their servers if you owned the game, presumably implemented for playtime tracking while offline

When you play a game via family sharing, your achievements and playtime get tracked on the Steam servers and can be viewed online, but nothing shows up for Cult of the Lamb for me

The steam_api file could be a proof of a simple "copy/paste" from steam to GoG, and could be concidered a lazy work to bring the game to us, but again I don't see how it could be GoG's fault.
And again, Steam is at blame as they still have not correctly locked their plateforme to prevent this kind of "semi integration". (after more than 18 years of existence)
Steam have a long habit of taking years and years to do basic fixes and very basic implementations. (it took them over 10 years to let you choose the drive for games installations) Considering their financial and work power (and the origin of their buziness), Valve's behavior is shameful.

Okay we get it, you don't like Valve, and that seems to be the only point you have to make. That is not why this thread is here. I'm not saying it is "GOG's fault", whatever that even means, I'm simply pointing out that it is a quirk that specifically exists in the GOG release, on the most relevant forum to discuss it, so that maybe the devs will notice and put it on the (no doubt lengthy) post-launch to-do list.

I do not "hate Valve", if I hate something that's some of their decisions, even less "for the pleasure to hate" (I have more than 800 games on Steam, it would be stupid to "hate" but still giving money, don't your think ?)
I point out bad decisions or inactions with the fact that this compagny have a pretty strong dev and monetary force, and almost 20 years behind the Steam-shop launch. So I point out bad actions, this is not related to "love or hate".

The weird part is that you are pointing out an issue related to Steam (that's steam who is going weird, not the game, neither Galaxy), and still come to GoG to "report" it... (plus the fact that game's devs will probably don't come to read anything on this forum before a while, if not never)
The release "version" is more or less exactly the same between GoG and Steam (we can suppose this by the presence of the steam files), and this cause an issue only on steam. So I speak from those facts.

If the only conclusion you can take from what I'm trying to say is that I "just don't like valve", you have a very strange (and inefficient) way of thinking...
If I was just bashing valve, It would take 1 phrase and I would not even bother trying to understand what is causing this.

I bought the GOG release. I am running the GOG release. Something in the GOG release is inciting weird behavior from Steam. We can probably take an educated guess that it is something about Steam files included in the GOG release that is causing this behavior, but it's anyone's guess as to whether that's an oversight on the devs' part that could be fixed in 30 seconds, or would require weeks of effort untangling it from the code it's tied into. My options are:

- post about it here where nobody ever goes but it's readily visible if anyone does come here
- post about it in the Steam discussion forums and, most likely, be told to go post about it on the GOG forums because that's where I bought it, then the thread gets buried inside of 20 minutes and is never seen again
- dig up some means of emailing someone at Valve and tell them about how their API is doing weird stuff in a release of a game on a different platform that probably shouldn't have those files included in the first place
- see if I can email the devs directly

That last one might not be a bad idea, but in the meantime this is the least stupid option afforded to me.

Yeah this is weird... my brother has this on steam and I get it through family share, the thing is I bough it on GOG but if he goes to play any game on steam it closes my GOG game as steam cuts family share while hes playing, wtf.

I just want to make a friendly suggestion: you have the option to post your issue on the game's discord channel. I think there you can find good visibility on your problem.

Good idea, thanks. I tend to forget some devs actually pay attention to some discords.