Why is this game not on GOG? I don't get it. What possible reason could the publishers have to keep it out of GOG?

No idea why not here but vote here: https://www.gog.com/wishlist/games/styx_shards_of_darkness

GOG is not the focus of the publisher. They haven't bothered releasing anything here ever since 2014.

Neither are Styx: Master of Shadows and Of Orcs and Men (the two previous games in the series). Since Cyanide Studios games appear to be DRM-free on Steam, maybe GOG can have another go?

It is DRM free on Steam but they didn't bring it to GOG? Do they hate money or maybe GOG specifically??? Voted :)

Sorry to say but it wouldn;t be the first one.

But they used to like GoG:

https://twitter.com/CyanideStudio/status/872454122674507776

Voted - we can always dream. I enjoyed Master of Shadows

it makes zero sense!

I'm very curious about this game. What is the gameplay like? Is it similar to Hitman, Commandos, Thief, something else? Both Styx games have quite good reviews on Steam.

It's very much a "hardcore" stealth game like the early Thief 1-2 games. There's a strong emphasis on stealth and a strong penalty for getting caught up in combat. There's sort of "Dishonored like" assassinations and you can use your environment against enemies (eg, drop chandeliers on people's heads, push guard's off high ledges, poison guard's food, etc). Although some levels seem a bit repetitive (a few later ones are the same maps as earlier but you go through them in reverse), they are also well known for having one of the most "vertical" map designs and give you a lot of "height" to play with which really adds to the stealth. You can also quick-save anywhere and they are fairly well optimized in terms of frame-rates.

Personally I liked them and I'd definitely buy another DRM-free copy if they ever came to GOG.

I'd suspect it's not Cyanide but the publisher. Aarklash Legacy was self-published, Styx, Of Orcs and Men etc. are published by Focus Home Interactive instead. And while Focus Home Interactive also has a few games on GOG, they seem to prefer just publishing on Steam. There's a similar looking case with Swing Swing Submarine - Blocks That Matter and Tetrobot & Co. were self-published by the devs and available everywhere DRM-free, then they signed a deal with Focus Home Interactive for Seasons After Fall, and now it's Steam only. I politely asked Swing Swing Submarine about that, but they just replied they had no clue whether there would be a DRM-free version for Seasons After Fall since they teamed up with a publisher for that one.

If the publisher says no then I guess there's not much the developer can do about it, no matter how pro-GoG they are.
Hopefully Focus Home will eventually come to their senses.

THQ Nordic releasing a handful of their bigger games on GoG on what looks like day 1 might actually convince other european publishers to follow suit, who knows?

This game turned to shit after Dennis DeYoung left.

voted.
Selling on more platforms should bring more money, so everyone should be happy- the publishers included.