Although publishers try to send everything to the English speaking international market in a fitting way, there is always a noticable difference in the overall style and symbolism of the games and the quality of translations.
I like to play games (and watch movies... and read books) in the original language if possible and felt quite stupid when seeing afterwards, that something wasn't English in the original version but I had this one and sometimes I notice missing or badly translated wordplays.
Anyway, I'd like to have an overview of games published on GoG sorted by the geographic (and cultural of course) origin.

Edit: Thanks to ddickinson for the biggest part of this list. :)
USA and UK had to be removed due to post length.

Feel free to discuss.
PS: Why are not the German versions of the Black Eye games from Deadalic here?
(Namely Chains of Satinav and Memoria)

Europe

Austria
Neighbours from Hell Compilation
The Nations Gold Edition
Alien Nations
Schein

Belgium
Outcast
Beyond Divinity
Divine Divinity
Divinity 2: Developer's Cut
Divinity: Dragon Commander
Divinity: Dragon Commander Imperial Edition
Divinity: Original Sin

Bulgaria
Celtic Kings: Rage of War
Omerta: City of Gangsters (4 Dlcs Included)
Omerta: City of Gangsters Gold Edition
Tropico 3 Gold Edition
Tzar: The Burden of The Crown

Croatia
Serious Sam: The First Encounter
Serious Sam: The Second Encounter

Czech Republic
Botanicula
Inquisitor
Machinarium: Collector's Edition
The Black Mirror 1
Ufo: Afterlight
Ufo: Aftermath
Ufo: Aftershock

Denmark
99 Levels to Hell
Chronology
Expeditions: Conquistador
Gangland
Hitman 1: Codename 47
Hitman 2: Silent Assassin
Hitman 3: Contracts
Rise of The Triad (2013)
Total Overdose: a Gunslinger's Tale in Mexico

Finland
Alan Wake
Alan Wake's American Nightmare
Crimsonland
Driftmoon
Flatout
Flatout 2
Legend of Grimrock
Lucius
Shadowgrounds
Shadowgrounds Survivor
The Swapper
Trine
Trine 2: Complete Story

France
Aarklash: Legacy
Alone in The Dark 1+2+3
Alone in The Dark: The New Nightmare
Amerzone - The Explorer's Legacy
Another World: 20th Anniversary Edition
Arx Fatalis
Atlantis 1: The Lost Tales
Atlantis 2: Beyond Atlantis
Atlantis 3: The New World
Blocks That Matter
Corsairs Gold
Darkstone
Dracula 4+5
Dracula Trilogy
Dragon Lore: The Legend Begins
Driver: Parallel Lines
Ethan: Meteor Hunter
Evoland
Fahrenheit (Indigo Prophecy)
Gobliiins Pack
Gray Matter
Iron Storm
Ishar Compilation
Little Big Adventure 1 (Relentless: Twinsen's Adventure)
Little Big Adventure 2 (Twinsen's Odyssey)
Megarace 1+2
Megarace 3
Moto Racer
Moto Racer 2
Moto Racer 3
Omikron: The Nomad Soul
Outlast
Pod Gold
Post Mortem
Prince of Persia: The Sands of Time
Prince of Persia: Warrior Within
Puddle
Raiden Legacy
Rayman 2: The Great Escape
Rayman 3: Hoodlum Havoc
Rayman Forever
Rayman Origins
Return to Mysterious Island
Robinson's Requiem Collection
Silver
Sniper Elite: Berlin 1945
Soulbringer
Space Run: Fast and Safe Delivery
Speed Busters: American Highways
Still Life
Still Life 2
Syberia
Syberia 2
Tetrobot and Co.
Time Commando
Wargame: European Escalation

Germany
1954 Alcatraz
A New Beginning - Final Cut
Aquanox
Aquanox 2: Revelation
Battle Isle Platinum (Includes Incubation)
Battle Worlds: Kronos
Beatbuddy: Tale of The Guardians
Blackguards Special Edition
Ceville
Clarc
Cultures 1+2
Cultures: Northland + 8th Wonder of The World
Darkstar One
Deponia 1
Deponia 2: Chaos on Deponia
Deponia 3: Goodbye Deponia
Desperados 1: Wanted Dead or Alive
Desperados 2: Cooper's Revenge
Edna & Harvey: Harvey's New Eyes
Edna & Harvey: The Breakout
Far Cry
Giana Sisters: Rise of The Owlverlord
Giana Sisters: Twisted Dreams
Gothic
Gothic 2 Gold Edition
Gothic 3
Heretic Kingdoms: The Inquisition
Heritage of Kings: The Settlers
Jack Keane
Jack Keane 2: The Fire Within
Jack Orlando: a Cinematic Adventure (DC)
Knights and Merchants: The Peasants Rebellion
Panzer Elite Special Edition
Patrician 1+2
Patrician 3
Port Royale
Port Royale 2
Realms of Arkania 1+2
Realms of Arkania 3
Risen
Risen 2: Dark Waters
Risen 2: Dark Waters Gold Edition
Robin Hood: The Legend of Sherwood
Sacred 1 Gold
Sacred 2 Gold
Smugglers V
Spellforce 2: Demons of The Past
Spellforce 2: Dragon Storm
Spellforce 2: Shadow Wars
Spellforce Platinum
The Black Mirror 2
The Book of Unwritten Tales
The Book of Unwritten Tales: The Critter Chronicles
The Guild 2
The Guild 2: Pirates of The European Seas
The Guild 2: Renaissance
The Guild Gold Edition
The Inner World
The Night of The Rabbit
The Raven - Legacy of a Master Thief
The Settlers 2: 10th Anniversary
The Settlers 2: Gold Edition
The Settlers 3: Ultimate Collection
The Settlers 4: Gold Edition
The Whispered World: Special Edition
Tiny and Big: Grandpa's Leftovers
Where Is My Heart?
The Dark Eye - Chains of Satinav[/url] (Not available here in German, wtf?)
The Dark Exe - Memoria[/url] (No original version on GoG either oO)

Hungary
1nsane
Dream Pinball 3D
Haegemonia Gold Edition
Nexus: The Jupiter Incident
Screamer 4X4

Ireland
Montague's Mount

Italy
Beyond Good and Evil
Screamer
Screamer 2

Netherlands
Age of Wonders
Age of Wonders 2: The Wizard's Throne
Age of Wonders 3: Deluxe Edition
Age of Wonders: Shadow Magic
Luftrausers
Overlord + Raising Hell
Reus
The Chaos Engine

Norway
Among The Sleep
Dreamfall: The Longest Journey
I.G.I. 2: Covert Strike
Teslagrad
The Longest Journey

Poland
Anomaly Defenders
Anomaly Warzone Earth
Downfall
Earth 2140 Trilogy
Earth 2150 Trilogy
Earth 2160
Gorky 17
MouseCraft
Painkiller Black Edition
Shadow Warrior (2013)
Teenagent
The Cat Lady
The Witcher 1: Enhanced Edition
The Witcher 2: Assassins of Kings
The Witcher 3: Wild Hunt - Preorder
Two Worlds
Two Worlds 2: Epic Edition

Slovakia
Gomo
Chaser
Heretic Kingdoms - The Inquisition
Battle Isle - Andosia Wars

Spain
Blade of Darkness
Commandos 2+3
Commandos Ammo Pack
Gods Will Be Watching
Imperial Glory
Praetorians
Runaway 1: A Road Adventure
Runaway 2: The Dream of The Turtle
Runaway 3: A Twist of Fate
The Last Door: Collector's Edition
Unepic

Sweden
A Story About My Uncle
Amnesia: The Dark Descent
Enclave
Ground Control + Expansion
Ground Control 2: Operation Exodus Se
Hammerwatch
Hotline Miami
Ittle Dew
Pid
Pinball Gold Pack
Pure Pinball 2 Redux
Shelter
Steamworld Dig
Stick It to The Man!
The Ball
The Chronicles of Riddick: Assault on Dark Athena
The Penumbra Collection
The Samaritan Paradox
Unmechanical

Switzerland
Journey of a Roach

Ukraine
American Conquest + Fight Back
Cossacks Anthology
Heroes of Annihilated Empires
Humans Must Answer
Journey to The Center of The Earth
Magrunner: Dark Pulse
S.T.a.L.K.E.R.: Call of Pripyat
S.T.a.L.K.E.R.: Clear Sky
S.T.a.L.K.E.R.: Shadow of Chernobyl
Sherlock Holmes: Secret of The Silver Earring
Soldiers: Heroes of World War II
_______________
Asia

China
American Mcgee's Grimm
Capitalism 2
Capitalism Plus
Restaurant Empire
Seven Kingdoms 2
Seven Kingdoms: Ancient Adversaries

India
Gothic 3 - Forsaken Gods - Enhanced Edition
Unrest

Japan
Blazblue Calamity Trigger
Deadly Premonition: Director's Cut
La Mulana
Street Fighter Alpha 2
The Legend of Heroes: Trails in the Sky
Unholy Heights

Malaysia
Vertical Drop Heroes Hd

Russia
Alien Shooter + Expansions
Alien Shooter 2: Reloaded
Blitzkrieg 2 Anthology
Blitzkrieg Anthology
Braveland
Eador: Genesis
Eador. Masters of The Broken World
Etherlords
Etherlords 2
Fantasy Wars
Heroes of Might and Magic 5: Bundle
Il-2 Sturmovik: 1946
Jagged Alliance 2: Wildfire
King's Bounty: The Legend
King’s Bounty: Crossworlds Goty
Knock-Knock
Pathologic
Perimeter
S2: Silent Storm Gold Edition
Star Wolves
Zombie Shooter
Zombie Shooter 2
_______________

South Africa

7th Legion
Desktop Dungeons

_______________

Australia

Dark Reign + Expansion
Krush Kill 'N Destroy Xtreme
Krush Kill ‘N Destroy 2: Krossfire
Fractured Soul
Dustforce
Influx
Warlords Battlecry 3
Flight of The Amazon Queen
Powerslide
Zafehouse: Diaries
Warlords Battlecry
Warlords Battlecry 2
_______________

America

Argentina
Scratches Director's Cut

Brazil
Mr. Bree+

Canada
Assassin's Creed: Director's Cut
Baldur's Gate - The Original Saga
Baldur's Gate 2 - Complete
Capsized
Disciples 1: Sacred Lands Gold
Disciples 2 Gold
Don't Starve
Dyad
Far Cry 2: Fortune's Edition
Fez
Fract Osc
Guacamelee! Gold Edition
Incredipede
Jade Empire
Jazzpunk
Mark of the Ninja
Mdk 2
Neverwinter Nights - Diamond Edition
Neverwinter Nights 2- Complete
O.R.B. Off-World Resource Base
Prince of Persia
Prince of Persia: The Two Thrones
Retro City Rampage
Rogue Legacy
Sang-Froid: Tales of Werewolves
Shattered Steel
Signal Ops
Slender: The Arrival
Space Pirates and Zombies
Super Puzzle Platformer Deluxe
Sword of The Stars: The Pit Gold Edition
Tales from Space: Mutant Blobs Attack
The Consortium: Master Edition
The Real Texas
To The Moon
Tom Clancy's Splinter Cell
Windforge

Uruguay
Kingdom Rush

Slovakia
Gomo
Chaser
Heretic Kingdoms
Battle Isle: Andosia Wars

Czech Rep
UFO games
Botanicula
Machinarium
Black Mirror (only the 1st)

Poland
Earth 2140-2160
Anomaly Warzone Earth
Anomaly Defenders
Gorky 17
Teenagent
Two Worlds 1-2

I have a big list of GOG game and their origins. I used the developer listed by GOG on the game page so some may be wrong, or I may have made a mistake, but I think most are correct. I made the list of games for my Great Nations Giveaway so I would know what countries have games on GOG.

I will PM you the list, since it will not let me post it here, even over multiple posts.

They are not necessarily translations.

While quite a few games are developed in Denmark, the original language is still English. To the best of my knowledge, no games are developed in Danish. Even if a Danish developed game has Danish localization, you can be sure that it was actually developed in English, then localized afterwards.

Danish, as a language, is too small to cater for exclusively, game-wise. If you want to sell a game, you can't make it Danish-only, especially since most Danes (other than children) prefer to play games in English, or doesn't care either way. Since you will always be able to sell many more English copies than Danish ones, it only makes sense to focus on the language with the most sales.

Also, just because a developer is located in a certain country, it doesn't mean that the games they develop are intended primarily for the local market. Often, a publisher is calling the shots. Take IO Interactive, for instance. A Danish development studio, yes, but owned by Square Enix. Why would Square Enix finance the development of games in Danish?

It sounds like what you are actually after is a list of games which have been localized into English, which is quite a different thing from what you asked.

If you understand the explanation how I got the idea this way, then feel free to ignore it.
Of course it's always interesting to hear more about the original languages, but even if the original language of the game is English, you often hear if it's not the original language of the devs.
BTW: I want to differentiate between producer and developer as far as possible.


Edit: Drat! I had to remove USA and UK due to maximum post length, maybe I should exclude English (first language) speaking countries after all.