Officially confirmed by GOG games (mostly the upcoming games' list from the front page):

Battletech
Battlezone: Combat Commander (remaster of Battlezone II)
Children Of Morta
Chuchel
Descent: Underground ( Info about why it's not IN DEV anymore)
Eitr
Frostpunk
Gwent Thronebreaker
Hellmut: The Badass From Hell
Heroes Of Hammerwatch
Iconoclasts
Into The Breach
Little Nightmares: Secrets Of The Maw expansion pass
Need To Know
Phantom Doctrine
Pillars Of Eternity 2: Deadfire
Soul Saga
Star Control: Origins
State Of Mind
System Shock Remake
The Swords Of Ditto
The Universim (in dev, but can't acquire yet)
Wildfire
Ys VIII: Lacrimosa Of DANA
Zwei: The Arges Adventure

IN DEV:

Airships: Conquer The Skies
Besiege
Crosscode
Dead Cells
Deep Sky Derelicts
Exanima
Factorio
Ghost of a Tale
Jalopy
Kenshi
Last Leviathan, The
Parkitect
Planet Nomads
Prodigy Tactics
Production Line
Project Zomboid
Riot: Civil Unrest
Sunless Skies
Tangledeep
Terratech
The Guild 3
We Happy Few (Possible release date April 13 2018 from developer's twitter)
Wolcen: Lords Of Mayhem

For me "in dev" is having access to a game to help make it better for release. When it leaves "in dev" is when I'll take it off this list because it released officially.

Unofficially confirmed games:

Since most of the games will come from:
https://www.gog.com/forum/general/games_that_are_unofficially_confirmed_for_release_in_the_future_part_2/
instead of putting the complete link to the source of the information, I will write the number of the post that came from that thread, you'll then need to copy the above link and add what I wrote after "source". There may be two post numbers written after the source, the first number is the original mention of the game and the second number is the latest "informative" post about it. Any information that comes from another source than the above thread will have a direct link provided. This is to be able to fit more titles in one post.

The games are separated by year it was last mentioned with "information" about it. If you feel a game is missing or don't agree with a game being here, tell me why and I might reconsider. People that only give links to information about a game without writing the name and some info won't see it appear here if no one else gives the info.

I would like to thank Andrey82 for giving me permission to keep an unofficially confirmed list of my own and for providing the list in the above thread. If he ever wishes for me to stop providing a list here, I will.

2017

15 Days -Source: post7452
911 Operator -Source: post6250
Army Men: Air Tactics -Source: post7452
Ash of Gods: Redemption -Source: post6680
Astroneer -Source: post3280 post6166
Bioshock series -Source: post6623
Black Annex -Source: post1280 post6166
Blasphemous -Source: post6789 post7007
Carnivores Games -Source: post6151
Codename Panzers: Cold War -Source: post3280 post6166
Cold Waters -Source: post7738
Constructor HD -Source: post1792 and here
Copper Dreams -Source: post6960
Cultist Simulator -Source: post7314
Cyberpunk 2077 -Source: post22 post6316
Defender's Quest 2 - Source: post159 post6166
Demons Age -Source: post3280 post6166
Door Kickers: Action Squad -Source: post7603
Dragon Fin Soup -Source: post3280 post6166
Drakensang -Source: post7452
Entymology -Source: post6356 Is that even a game?
Excubitor -Source: post3280 post6166
Forsaken - Source: post73 post6080
Forsaken Castle -Source: post6685
Grav -Source: post3280 post6166
Has Been Heroes -Source: post6506
Hellpoint -Source post6486 post6621
High Hell -Source: post7380
Keen Dreams -Source: post7352
Kill To Collect -Source: post3280 post6166
Legrand Legacy -Source: post7400
Life Is Feudal: Your Own -Source: post3280 post6166
Medieval Engineers -Source: post3280 post6166
Milanoir -Source: post7206
Northgard -Source: post6265
Opus Magnum -Source: post7624
Oriental Empires -Source: post7738
Orwell: Ignorance Is Strenght -Source: post7230
Paradise Lost: First Contact -Source: post6163
Pathfinder Adventures -Source: post6840
Phoenix Point -Source: post6600
Pizza Connection 3 (Pizza Tycoon 3) -Source: post7310
Planetary Annihilation: TITANS -Source: post3280 post6166
Red Comrades Save the Galaxy: Reloaded -Source: post7041
Redeemer -Source: post6227 post6254
Rise & Shine -Source: post7288
Sacred Fire -Source: post6417 post6429
Savage Lands -Source: post3280 post6166
Senran Kagura Shinovi Versus -Source: post3280 post6166
Shadows: Awakening -Source: post7270
Space Engineers -Source: post3280 post6166
Stardrive -Source: post3280 post6166
Stardrive 2 -Source: post3280 post6166
Stifled -Source: post7452
Stranded Deep -Source: post3895 post6162
Sully: A Very Serious RPG -Source: post3280 post6166
The Banner Saga 3 -Source: post6128
The Franz Kafka Videogame -Source: post6347
The Legend Of Heroes: Trails Of Cold Steel 2 -Source: post6535 post7126
The Lion's Song -Source: post7735
The Mandate -Source: post172 post6166
The Neverhood -Source: post699 post6623
The Norwood Suite -Source: post7288
They Are Billions -Source: post6969
Tokyo 42 -Source: post7041
Tokyo Xanadu eX+ -Source: post7659
Town Of Light -Source: post3280 post6166
Treasure Adventure World -Source: post7214
Upwards, Lonely Robot -Source: post3280 post6166
White Day: A Labyrinth Named School - Source: post7341
Wizardry 1-5 -Source: post6695
Worlds Of Magic -Source: post109 post6320 (probably won't come)
Xenonauts 2 -Source: post6173 post6282
Yonder: The Cloud Catcher Chronicles -Source: post7058
Zeno Clash -Source: post3280 post6166

2016 --- 2015 --- 2014 - 2013

Episodic games / Episodic DLCs we're waiting on:

If I'm missing anything point it out.

Batman: The Enemy Within (Season 2) -- Episodes: 4 -5
Ken Follett's The Pillars Of The Earth Episode 3
Kentucky Route Zero -- Act: 5
Little Nightmares -- DLCs: 3
The Long Dark Season 1 episodes 3 -4 -5

Anyone knows if Strafe's release date was pushed to May or if it's still supposed to release the 28th of march? I'm more inclined to trust Metacritic with the may 9th date than GOG (because pushbacks happens so often). Anyone knows?

Definitely delayed, May 9th is the new date.

Thanks! Correcting the info.

No problem! And the price will be $19.96, because of the year.

The game will actually release tomorrow. March 28th is only for the US physical retail/digital console release.

Unofficially confirmed games

2016

Ancient Domains Of Mystery Deluxe -Source: post1181 post4672
Arakion -Source: post4906
Arcadian Atlas -Source: post2642
Battlestation: Harbinger -Source: post3182
BattleTanx -Source: post2904 post4479
Brawl -Source: post4593
Captain Quazar -Source: post2904 post4479
Carmageddon: Max Damage -Source: post3180
Crush Your Enemies -Source: post4356
Devil's Daggers -Source: post2817
Dinocide -Source: post2799
Door Kickers 2 -Source: post2952
Ghost 1.0 -Source: post3745
Hammer And Sickle -Source: post3811
Her Majesty's SPIFFING -Source: post5495
Insanely Twisted Shadow Planet -Source: post4553
Jay and Silent Bob: Chronic Blunt Punch -Source: post2740
KeeperRL -Source: post2809
Kingdom Come: Deliverance -Source: post2506
Niffelheim -Source: post3280
Nightcry -Source: post2892
Postal 2: Paradise Lost DLC -Source: post1567 post4018
Project Resurgence -Source: post4279 (studio dissolved, they *might* still do the game, but I'm not following it anymore)
Reflections -Source: post4279
Rhem 1 -Source: post2638
Rhem 4 -Source: post2638
Scorn -Source: post4618
Shrouded In Sanity -Source: post4279
State Of Decay: Year One Survival Edition -Source: post4219 post5107
Subnautica -Source: post3452
The Bunker - Source: post4880
The Count Lucanor -Source: post2963
The Fall Of Lazarus -Source: post4577
The Pit -Source: post3280 (Is this the iOS game or the card game? Unsure if I should count it as released or not)
The Political Machine 2016 -Source: post3280
The Quest -Source: post2465 post2525 (Rejected)
Wasteland 3 -Source: post5469 post5607
Way Of The Samurai 3 -Source: post3035 post3811

Unofficially confirmed games

2015

2Dark -Source: post1627
Albert & Otto (Episode 1) -Source: post1985 (Is this game completed? Are they making only poop games now?)
American McGee's Scrapland -Source: post1451
Axiom Verge -Source: post1571
Bard's Tale IV -Source: post1677
Black Ice -Source: post1222
Bloodstained: Ritual Of The Night -Source: post1679 post1680 GOG
Call Of Cthulhu: The Wasted Land -Source: post2396 post2399 (Rejected, Unavailable because of licensing problems)
Cogmind -Source: post1771
Curse Of Monkey Island -Source: post1673
Decay: The Mare -Source: post1283
Edge Of Eternity -Source: post1321
First Wonder -Source: post2039
Frontiers -Source: post1704
Garbage Day -Source: 2203
Legends of Dawn -Source: post138 post2268
Luckslinger -Source: post1758
Mugen Souls -Source: post2171
Paradise Never -Source: post1373
Psychonauts 2 -Source: post2377
Seven Dragon Saga -Source: post1399 (Cancelled)
Shakedown Hawaii -Source: post2350
Shallow Space: Insurgency -Source: 1612
Son Of Nor -Source: post1479
Stars Beyond Reach -Source: post2088
Tengami -Source: post1313
They Bleed Pixels -Source: post1684
The Consuming Shadow -Source: post1788 post2075 (Rejected)
Vertiginous Golf -Source: post1513

Unofficially confirmed games

2014

Children Of Liberty -Source: post262
Gex 2 -Source: post1089
Gex 3 -Source: post1089 1101 (Probably not)
Gold Rush! - Source: post764
Legions Of Ashworld -Source: post32 post684 (Rejected?)
Machines At War -Source: post688 post810 (Rejected)
Manos: The Hand Of Fate -Source: post1059
Mims -Source: post1072
Shiness -Source: post541
Star Command Galaxies -Source: post1139
Ultionus A Tale Of Pretty Revenge -Source: post263 post394
Woolfe: The Red Hood Diaries -Source: post828

2013

Cryamore -Source: post138
Deathfire: Ruins of Nethermore -Source: post172 (Cancelled)
Doorways -Source: post108
Fade To Black -Source: post138
Flashback -Source: post138
Iron Soul -Source: post30
Wreckfest (Next Car Game) -Source: post29
Planetary Annihilation -Source: post138
Routine -Source: post138
Silver Symbiosis -Source: post66 (abandoned project?)
Spud's Quest -Source: post65
The Dream Machine -Source: post138
Trial By Magic -Source: post138
Two Guys SpaceVenture -Source: post138

Latest updates:

Calendar

Removed 88 Heroes, March 24 2017
Removed Vikings - Wolves Of Midgard, March 24 2017

Added Rain World, March 28 2017
Added The Franz Kafka Videogame, April 6 2017
Added World Of The West, May 5 2017

Unofficially confirmed games

Added all the lists.

Some things I need clarifications on:

Are the games Planetary Annihilation and Planetary Annihilation: TITANS one and the same? Referred to and [url=https://www.gog.com/forum/general/games_that_are_unofficially_confirmed_for_release_in_the_future_part_2/post6166]here.

How many Carnivores games are there? Referred to here.

Is the game King's Quest referred to a sequel of the games we already have [url=https://www.gog.com/game/kings_quest_1_2_3]here?