Owlcat's new CRPG Warhammer 40k Rogue Trader coming to GOG at launch.

Alpha 2022, Beta 2023 (unsure what platforms the alpha/beta will be).

https://roguetrader.owlcat.games/preorder/en/faq

A sub-forum has appeared for Wadjet Eye Games' upcoming title Old Skies:
https://www.gog.com/forum/old_skies

The dev of retro fantasy FPS Wizordum would like to bring the game to GOG:
https://twitter.com/wizordum/status/1532123243305480192

And the dev of cyberpunk detective game Let Bions be Bygones is open to bringing the game to GOG:
https://twitter.com/BohemianPulp/status/1532131597922746371

Bit of a departure from their usual pixely aesthetics:
https://www.youtube.com/watch?v=oqhuyKIy9-U

On Reddit, I''d asked the dev of Outmode if they had any plans on releasing the game on GOG. The dev said, "No current plans to be on GOG, but I'll see if anymore people request that!".
Here is the link to the conversation:
https://www.reddit.com/r/pcmasterrace/comments/v3w6tn/over_the_last_2_years_ive_been_working_on_a_retro/ib3tis2/?context=8&depth=9

Also, for anyone interested in wishlisting the game:
https://www.gog.com/wishlist/games/outmode

Chronicles of 2 Heroes - a 16bit metroidvania made by Infinity Experience will show up on GOG.

https://www.kickstarter.com/projects/projectjapan/chronicles-of-two-heroes-amaterasus-wrath

An entry for Roguebook has been found deep in the bowels of the GOGwhale. Fear ye not, I'll head back below and search for more :P.

Summary:

GOG database (these games were detected a long time ago, they were probably scrapped for some reason):
Hummingwarp Interactive - Secret Little Haven
Sonalysts - Fleet Command, Sub Command, Dangerous Waters, 668(I) Hunter Killer
Something We Made - Toem
拾英工作室 - Tales of the Black Forest
Random Games Inc., MPS Labs - Wages of War (?)

Sub-forums:
Serious Sam 2 (Now hidden)
Serious Sam 3 (Now hidden)

Hidden GOG data:
Mafia: Definitive Edition
Senran Kagura Shinovi Versus
Lumberhill
HITMAN 2 Gold Edition
Prince of Qin
Pronty
Roguebook

GOG logo on websites/trailers:
The Lost Wild
Blight: No Man's Land
Crisis in the Kremlin
PRIM
Frozenheim
Warhammer 40,000: Rogue Trader

Press sites:
Fata Deum
World Championship Boxing Manager II
SunnySide
Miasma Chronicles
Trinity Trigger

Discord, Twitter (The dev has already contacted GOG):
ANNO: Mutationem
SCORN
Eiyuden Chronicle: Hundred Heroes
The Darkest Tales - Into the Nightmare
Szrot
Forest Grove
Drova - Forsaken Kin
Meat Puppet
INCANTAMENTUM
Sea Dogs: Legendary Edition
darkwebSTREAMER
Future Fragments
Westwood Shadows
Brutal Orchestra
Unfortunately Ninja
Chronicles of 2 Heroes

Discord, Twitter (The dev would like to):
REKKR: Sunken Land
Instruments of Destruction
Islands of the Caliph
Dangerous Dave: Champion's Edition
Dying Breed
XEARZ
Spire of Sorcery
Supplice
Madshot
Coromon
Dune: Spice Wars
Prehistoric Kingdom
Trial Out
Dark Quest: Board Game
Wildermyth
Wizordum
Let Bions be Bygones
Voodoo Detective

Legacy hidden GOG data (these games were detected a long time ago, they were probably scrapped for some reason):
Assassin's Creed 2
Assassin's Creed 3
Skyrim
Civilization V
Wages of War
Army Men: Air Tactics
Army Men: Sarge's Heroes
Army Men: Sarge's War
The Abbey
RAGE
Culpa Innata
Battle vs Chess
Fleet Command
Bound By Love

Sub-forum was added for Eiyuden Chronicle: Hundred Heroes:
https://www.gog.com/forum/eiyuden_chronicle_hundred_heroes

And FunBox Media says that they will be bringing more titles such as ERacer to GOG:
https://twitter.com/FunboxMediaLtd/status/1533162184871641089

Technically official but has yet to arrive on the startpage
https://www.gog.com/forum/general/sega_partnering_with_gog_eaba8
Link is now 404 but it was a thread telling that game such as Alien Isolation, Two Point Hospital and I think Warhammer 40K Dawn of War will arrive to GOG.

and more soon announced in the futures weeks

I believe it was Warhammer 40k Space Marine Anniversary Edition that was the third game mentioned.

This thread was posted too early because it said Alien Isolation is available now. Will probably arrive in an hour (likely with summer sale start).

And yes it was Space Marine not DoW sadly :/

You're correct now when I think about it, unfortunately.

Space Marine is perfectly fine with me. It's a good action game.

Still, DoW is what I REALLY want.

Well, it said "more Warhammer classic games coming soon to GoG" so it can't be just the original Space Marine.
Doesn't confirm the Dawn of War series just yet either (the classic Space Hulk, Space Crusade or HeroQuest games are possible candidates as well) but they could show up sometime further down the line.
If you were able to wait for this long you surely can do it a little longer.