Alexim: Let us open the thread with a summary of what we know so far:

Hidden GOG data (Galaxy API):
Receiver 2
Soulstice
Time Lock VR-1
Titanium Hound
Shadow of the Guild
Monster Outbreak
Smutty Scrolls
Aquatico
SCP: Secret Files
Bug Academy
Warstone TD GOLD Edition
Twin Mirror
GOBLiiiNS5
Mythargia
Beltane
Kandria (See also "Galaxy files in the Steam version")
Sujimon Quest
Squally
Kalyzmyr
3dSen PC (NES emulator)
Chicken Shoot
Chicken Shoot 2
Karma City Police
Pampas & Selene
Blade Prince Academy
The Library of Babel
Super Arcade Racing
Hell Is Us
DROP - System Breach
Skautfold: Shrouded in Sanity
Deleveled
College Bowl
New Cycle
WUCHANG: Fallen Feathers (See also "Galaxy files in the Steam version")
SANYA
Anomaly Agent
Murky Divers
CARNAL
Big Helmet Heroes
Azur Lane: Crosswave
BasketBelle
Battle Shapers
Cassette Beasts
Crusader Kings III
Deathloop
Detroit: Become Human
Empire of Sin
Escape From Norwood
Final Fantasy I
Final Fantasy II
Final Fantasy III
Final Fantasy IV
Final Fantasy V
Final Fantasy VI
Frog Detective 1 + 2 + 3
Heretic's Fork
Horizon Forbidden West
Iron Lung
Marvel's Spider-Man: Miles Morales
Panzer Dragoon II Zwei: Remake
Ratchet & Clank: Rift Apart
Realms of Magic
Resident Evil 4
Resident Evil Zero
Sifu
Smile For Me
Somerville
Tarnished Blood (See also "Galaxy files in the Steam version")
Teenage Mutant Ninja Turtles: Shredder’s Revenge
The Last of Us Part I
Toribash Next
Unknown 9: Awakening
Vampire: The Masquerade - Swansong
Wanted: Dead
Zipp's Café
Space Otter Charlie
The Ambassador: Fractured Timelines
Indiana Jones and the Great Circle

GOG logo on websites/trailers/official press releases:
The Lost Wild
Blight: Survival (Blight: No Man's Land)
Crisis in the Kremlin
Smurfs Kart (Released on Steam)
World of Anterra
Armed Fantasia
Penny Blood
Unreal Tournament 3 X
Akiba's Trip: Undead and Undressed Director's Cut
Medic: Pacific War
Ova Magica
Tiny Life (Released on Steam EA)
Cloudscape
Sang: The Desert Blade
Toasty Ashes of Dusk
Thief's Roulette
Hyper Team Recon
Elementallis
SteamDolls
Hero.EXE
Project Arrhythmia (Released on Steam EA)
Witchfall
The Girl From Arkanya
LAZR
Liam_99
Shattered: The Final Days (Released on Steam EA)
Dark Deity 2
Pathfinder: Abomination Vaults
Windswept
PRELUDE Dark Pain
RC Revolution
HYBERBOREA-12
beta decay
Ratatan
Offroad Mechanic Simulator
Space Invaders Deck Commander
Bloody Good Friends
Spooky's Jump Scare Mansion: HD renovation
NeoSprint
Neverlooted Dungeon
Catcelona
Totally Spies! - Cyber Mission (Released on Steam)
Nirvana Noir
Sky Oceans: Wings For Hire
Ra Ra Boom
Celestial Return
Shields of Loyalty
Deliver Us Home
Sam & Max: The Devil's Playhouse Remastered
☵ HIRAETH
Horn of Balance
Elements Destiny
W.A.N.D. Project
MÖRK BORG Heresy Supreme
Flesh Made Fear
Let Them Come: Onslaught
Furyball
Seed of Nostalgia
FIEFDOM
Quantic River
Bytebond
Hunter's Moon: A Sovereign Syndicate Adventure
Crux Diaries
Darkenstein 3D
Parasite Mutant
Kusan: City of Wolves
Lurks Within Walls

Press sites:
SunnySide (Released on Steam)
Commandos 3 - HD Remaster (Released on Steam)
Circus Electrique (Released on Steam)
Slow Damage
Caverns of Mars: Recharged (Released on Steam)
AirportSim (Released on Steam)
Consortium Remastered
Local News with Cliff Rockslide (Released on Steam)
DYSPLACED
Kickback Slug: Cosmic Courier (Released on Steam)
Lost Hellden
Randy & Manilla (Released on Steam)
Minicology (Released on Steam)
Yan: Parasomnia
IHAS (Released on Steam)
Monster Run (Released on Steam)
Danchi Days
HYPERxFANTASY
Shadows of Morhaven
Fretless - The Wrath of Riffson (Released on Steam)
Gnomes (Released on Steam)
Crown Gambit (Released on Steam)
Hungry Horrors
Slain 2
Ys X: Proud Nordics

The dev submitted the game to GOG:
NAIAD
Telly the TV
Monster Crown: Sin Eater
While We Wait Here
Beauty and the Thug
Oppaidius
Slayaway Camp 2
Paper Perjury
This Is Not Your House
The Necromancer's Tale

Discord, Twitter, Forums, Kickstarter (The dev has already been in contact with GOG):
Szrot
Forest Grove
Sea Dogs: Legendary Edition
darkwebSTREAMER
Westwood Shadows (Released on Steam EA)
Unfortunately Ninja
Chronicles of 2 Heroes (Released on Steam)
Zodiac Legion
Aerial_Knight’s Never Yield (Released on Steam)
Tears of Magic
CULTIC (Released on Steam EA)
The Grail
SP Grand Prix
Cats and the Other Lives (Released on Steam)
illucid
Streets of Rogue 2
Selaco
Demon Crush
Sword and Fairy 7 (Released on Steam)
Hibernaculum
D.O.R.F. Real-Time Strategy
Regions of Ruin 2
Hammerwatch II
Wandering Sword
Sirens
Jinn
Metropolis 1998
The Diner at the End of the Galaxy
Pixel Noir
Chicken Police: Into The Hive
The Transylvania Adventure Of Simon Quest
Paris Belle Epoque
Vampire Syndicate: Gangs of Moonfall
Dungeons Deep
Maple Forest
Soulash 2
Mind Healer: Aurora's Guilty Path
Butcher's Creek
VOIN
Inspector Schmidt - The Ebbing
Commandos: Origins
Rance IX
Bytes n Bolts: A Tech Shop Simulator
Without a Dawn
Tales From The Unending Void Season 2
Tunguska: Whitefall
Neyyah

Discord, Twitter, Forums, Kickstarter (The dev would like to):
Dangerous Dave: Champion's Edition
Dying Breed
XEARZ
Spire of Sorcery
Supplice (Released on Steam EA)
Dune: Spice Wars (Released on Steam)
Prehistoric Kingdom (Released on Steam EA)
Dark Quest: Board Game
Let Bions be Bygones
ERacer
Blossom Tales 2: The Minotaur Prince (Released on Steam)
Pixel Games UK (Publisher)
Flynt Buckler Wakes the Sleepy Castle
The Wayward Realms
Compound Fracture
GrandMa Badass (Released on Steam)
Who's Lila? (Released on Steam)
Guns Undarkness
Open the Gates! (Released on Steam)
Darkenstein 3-D
Poly Bridge 2 (Released on Steam)
Surviving the Humans
DESORDRE (Released on Steam)
Earth of Oryn
Final Upgrade
RetroSpace
微光之镜 Glimmer in Mirror (Released on Steam EA)
The Spirit of the Samurai
Alterium Shift (Released on Steam EA)
Aquatico (Released on Steam)
Relentless Frontier
Glasshouse
Darkness Within (Released on Steam)
We Who Are About To Die (Released on Steam EA)
Gone rogue (Released on Steam)
Exekiller
Summer Daze: Tilly's Tale (Released on Steam)
Roots of Yggdrasil (Released on Steam EA)
The Foretold: Westmark Legacy
Kerbal Space Program 2 (Released on Steam EA)
Intruder in Antiquonia (Released on Steam)
!Ω Factorial Omega My Dystopian Robot Girlfriend
Frigato - Shadows of the Caribbean (Released on Steam)
Clover Days
Death Corp.
Hellscreen (Released on Steam EA)
Blood Nova (Released on Steam)
The Adventures of Bryan Scott
Scarlet Deer Inn
Galactix
DemonStar (Released on Steam)
Polars
Last Moon
The Villain Simulator
Fruitbus
Oxenfree 2 (Released on Steam)
Keep the Keep
SORCERESS
Shadows of the Afterland
Chronicles of the Wolf
Dust Front RTS
Mouse
Death Must Die (Released on Steam EA)
The Bloodline (Released on Steam EA)
Pioneers of Pagonia (Released on Steam EA)
Unbroken
Dread Delusions
Sunkissed City
Fancy Pants Enhanced
FUMES
KingMakers
Demise: Rise of the Ku’tan
Silence of the Siren
Clock Tower: Rewind
Ex-Zodiac
Cosmic Holidays
Cleared Hot
Tiny Glade
THRESHOLD
Megacopter: Blades of the Goddess
STAR BIRDS
Jupiter Hell Classic
Commander Bug Wars
Zero Below the Sun
Mid'âme
Gravelord
COVEN
VenusBlood GAIA International
Cyclopean
Motorslice
Neva
End's Reach
Zero Below the Sun
Beneath
The Long Dark
Sea Power
Everseeker: Little Critters
DEFICIT
Dungeons of Edera 2
Demon Tides
TAGAP: The Apocalyptic Game About Penguins
Thunder Helix
Roman Triumph: Survival City Builder
Nullstar: Solus
Preserve
Knights of the Crusades
Painted in Blood
Tunguska 2: Whitefall

Galaxy files in the Steam version:
Survival: Fountain of Youth
Tarnished Blood
Kandria
My Demonic Romance
Rocket Knight Adventures: Re-Sparked!
Mutant Football League 2
Phantom Spark
Golden Lap
HOCCO
Angeline Era
Jumanji: Wild Adventures
Elevator Down
Together in Battle
Run Heroes Run
URBO: Dream One
Dark Moon
GNOSIA
Rock Crusher
Neptunia Riders VS Dogoos
WUCHANG: Fallen Feathers
Little Nightmares III (Demo)

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
Civilization V
Wages of War
Army Men: Air Tactics
Army Men: Sarge's Heroes
Army Men: Sarge's War
The Abbey
RAGE
Culpa Innata
Lumberhill
HITMAN 2 Gold Edition
Dragon Throne
The Outforce
Poppy Playtime
Fleet Command
Sub Command
Bound By Love
FlatOut: Ultimate Carnage
FlatOut 3: Chaos & Destruction
Hummingwarp Interactive - Secret Little Haven
拾英工作室 - Tales of the Black Forest
Random Games Inc., MPS Labs - Wages of War (?)
Bus Simulator 18

Diem2: Miyoshi Shizuka wants to publish "Inner Truth" on GOG after Steam's ban: https://x.com/Miyoshi_Shizuka/status/1987672531776766406 .
GOG dreamlist link here: https://www.gog.com/dreamlist/game/inner-truth

Swedrami: The recently published glimpse at gameplay for Let Them Come: Onslaught (Tuatara Games) sports the GoG logo.

"Let Them Come: Onslaught strands players on an alien world overrun by horrors with only one way out — nuke it from orbit! Every choice of weapon and upgrade impacts your chances of survival. Fight against overwhelming odds until the timer hits zero and the nuke drops, leveling the battlefield in spectacular fashion.

This action-packed game offers a next-generation take on the Survivors-like formula where every battle is a desperate last stand, combining bullet hell chaos, deep progression, and brutal sci-fi horror with an ‘80s VHS aesthetic."