Let's see:

[HAVE]

GOG:
GIANTS: CITIZEN KABUTO
HEROES CHRONICLES: ALL CHAPTERS
WORMS FORTS: UNDER SIEGE
HEROES OF MIGHT AND MAGIC® 3: COMPLETE
Agarest: Generations of War
A Golden Wake
Blackwell Bundle
JAZZPUNK
Long live the Queen
Personal Nightmare
SImon the Sorcerer
Simon the Sorcerer 2
Simon the Sorcerer 3D
The Feeble Files
Torchlight
Waxworks

Steam:

3 Stars Of Destiny
18 Wheels of Steel: Extreme Trucker
99 Spirits: Special Edition
140
199X
1954 Alcatraz
6180 The Moon
A-Train 8
Abducted
Adventures of Shuggy
Akane the Kunoichi
Alpha Kimori™ 1
Alter World
Always Sometimes Monsters
Amazing Zombie Defense
Amygdala
Anachronox
A NEW BEGINNING - FINAL CUT
Antisquad
Ascension to the Throne
A Story About My Uncle
AVEYOND: LORD OF TWILIGHT
Axis Game Factory
Back to Bed
Ballpoint Universe - Infinite
Bardbarian
Barter Empire
BeatBlasters III
Ben There, Dan That
Beware Planet Earth!
Beyond Space
Biology Battle
Black Mirror
BlastZone 2
Bleeding Border
Blue Rose
Borealis
BoxesWithGuns
Breach & Clear
Bridge Constructor Playground
Bridge Constructor Playground
Cargo 3
Cave Coaster
Chicken Shoot 2
ChickenShoot / Kurka Wodna 2
Chronicles of the Witches and Warlocks
Clickr
Coin Crypt
Company of Heroes™ 2 - The Western Front Armies: US Forces
Crash Time 2
Crunch Time!
Cuban Missile Crisis + Ice Crusade Pack
Dark Scavenger
Darkstone
Dead Bits
Deadlands Noir - That Old Time Religion
Deadly Premonition: The Director's Cut
Death to Spies : Gold
Desert Law
Dino D-Day
Dragon Age™: Origins
Dragonsphere
Dream Tale
Droid Assault
Dungeons: The Eye of Draconus
Dysan The Shapeshifter
Edna & Harvey: Harvey's New Eyes
Electronic Super Joy
Endless Space
Endless Space Emperor Edition
Epigenesis
Etherlords II
EvilQuest
F-19 Stealth Fighter
Fairy Tale About Father Frost, Ivan and Nastya
Fake Colours
Fake Colours
Finding Teddy
Fitz The Fox
Forge Starter Pack
FOTONICA
Freedom Planet
Frozen Hearth
Ghostship Aftermath
GIANA SISTERS: TWISTED DREAMS
Go! Go! Nippon! ~My First Trip to Japan~
Go To Bed: Survive The Night
Governor of Poker 2 Premium Edition
Grimind
Guardians of Graxia: Elves & Dwarves DLC
Guardians of Middle-earth
Gun Metal
Hacker Duality
Heli Heroes Steam Key
Helldorado
Hexus
HOARD
HOARD
Hook
HotLead
Humble Origin Bundle 2
Huntsman
Industry Transporters
Instinct
Jack Orlando: Director's Cut
Jet Gunner
Journey of a Roach
Journey of a Roach
KickBeat Steam Edition
King's Bounty: The Legend
Kingdom Rush
Knights & Merchants
KnightShift
Ku: Shroud of the Morrigan
Legends of Solitaire: Curse of the Dragons
Leona's Tricky Adventures
Lilly and Sasha: Curse of the Immortals
Lily Looking Through
LITIL DIVIL
Little Big Adventure
Little Big Adventure 2
Loot Hero DX
LOST PLANET® 3
Louie Cooks
Mad Snowboarding
Magical Brickout
Mass Effect™ 2
Men of War: Red Tide
Men of War : Vietnam
Meridian: New World
MirrorMoon EP
Monster Loves You!
Monster RPG 2
Moorhuhn (Crazy Chicken)
Mosby's Confederacy
Munin
Mutant Mudds Deluxe
NekoChan Hero
NEO AQUARIUM - The King of Crustaceans
Neocolonialism
Never Ending Night
Nicole (Otome)Rogue Harvest
Nightmares from the Sea
Nightmares from the Sea
Nightside
Nosferatu: The Wrath of Malachi
Nosgoth Veteran Pack
Not the Robots
O3DX
Once Bitten, Twice Dead!
One Final Breath
One Finger Death Punch
Outland - Special Edition
Overture
Pahelika: Secret Legends
Papo & Yo
Peggle Deluxe, Bejeweled 3, Bookworm Deluxe, Escape Rosecliff Island, and Feeding Frenzy 2 Deluxe
Perfection
Pid
PixelJunk Eden
Pixel Piracy
Point Perfect
POSTAL Steam Key
Post Apocalyptic Mayhem
Predator Simulator
Pretentious Game
Professional Farmer 2014 - Platinum Edition
Project Tarvotan
Puzzler World
Q.U.B.E.
QUALIA 3: Multi Agent
Quarries of Scred
Quest for Infamy
Quest of Dungeons
Rabbit Hole 3D
Rage Runner
RAILYARD: MATCH-3 EVOLVED
Ravensword Shadowlands
Red Faction Guerrilla Steam Edition
Redshift Blueshift
Reign: Conflict of Nations
Rex Nebular and the Cosmic Gender Bender
ROCKETSROCKETSROCKETS
Rogue Harvest
Rush for Glory
S.T.A.L.K.E.R: Call of Pripyat
SanctuaryRPG: Black Edition
Sang Froid
Sea Legends: Phantasmal Light
Secret of the Magic Crystals Complete
SECTOR
Shelter
Sinister City
Sinking Island
Sky Mercenaries
Soulbringer
Spacechem
Spacechem
Star Nomad
Star Nomads
Starseed Pilgrim
Star Trek
STATIC: Investigator Training
Stay Dead Evolution
SteamWorld Dig
Straima
Strata
STRIDER™
Sugar Cube: Bittersweet Factory
Supercharged Robot VULKAISER
Super Slam Dunk Touchdown
Super Space Meltdown
Super Splatters
Sword of Asumi
Sword of The Stars: The Pit
Syberia II (game)
Syder Arcade
Symphony
System Shock 2
Tales From Space: Mutant Blobs Attack
Terra Nova: Strike Force Centauri
Tesla Breaks the World!
The Book of Legends
The Bureau: XCOM Declassified
The Cat Lady
The Culling of the Cows
The Language Game
The Nightmare Cooperative
The Oil Blue
The Original Strife: Veteran Edition
The UnderGarden
Thief Gold
Towers of Altrac
Tracks and Turrets
Type:Rider
Ultionus: A Tale of Petty Revenge
Umbra: Shadow of Death
Undeads
Unhack
Vanguard Princess
Vapour + Soundtrack Part 1 Edtion
Velocibox
Vertical Drop Heroes HD
Vox
Voyage: Journey to the Moon
War: The Game
Warhammer® 40,000: Dawn of War II
Warhammer® 40,000: Dawn of War® - Game of the Year Edition
Wickland
Witches, Heroes and Magic
World War I - Centennial Edition
XIII Century - Gold Edition
Yuri
Zombie Kill of the Week - Reborn

More valuable:
Amnesia Fortnight 2014
Call of Juarez 3: The Cartel
DarkBase 01 (not in Steam anymore)
Heavy Bullets + Extra Copy
Just Cause Collection
Legend of Grimrock
Morrowind GOTY
Of Orcs And Men
OlliOlli 2: Welcome to Olliwood
Rogue Legacy
Spec Ops: The Line
Star Wars™ Knights of the Old Republic™
Star Wars™ Knights of the Old Republic™ II
Star Wars™ Republic Commando
Tales from the Borderlands (Telltale Store key)
Valkyria Chronicles

Groupees' Be Mine 12 (containing Sang-Froid, Half-Minute Hero, Beatblasters III, Gun Metal, Bardbarian, A-Train 8, Echo of the Wilds, Epigenesis, Ilamentia and A New Beggining: Final Cut)
Groupee's Build a Casual Bundle 2 (Containing Criminal Minds, Doctor Who: The Adventure Games, Terra Incognita: The Descendant - Groupees Special Edition, Evil Pumpkin: The Lost Halloween, Miner Wars Arena, Dungeon of Elements, Tribloos 2, Paranormal State: Poison Spring, Murder, She Wrote 2, Atlantis: Pearls of the Deep)
Groupee's Spring Fling Bundle (Containing Nikopol: Secrets of the Immortals, Syberia, Syberia II, Post Mortem, Nostradamus: The Last Prophecy, Rhiannon: Curse of the Four Branches, Salammbô: Battle for Carthage, The Cameron Files: The Secret at Loch Ness, The Egyptian Prophecy: The Fate of Ramses, Necronomicon: The Dawning of Darkness, Amerzone: The Explorer’s Legacy. Curse: The Eye of Isis.Voyage: Journey to the Moon.Schein)
Humble Origin Bundle 2 - Origin keys
[WANT]

(either GOG or Steam is fine, when applicable. I can consider trading multiple games for one if it's something I really want)
Forgotten Realms Archives (especially volumes I and III)
Fran Bow
The Elder Scrolls: Battlespire
Dead State
Police Quest Collection
Final Fantasy III, IV
Shovel Knight
Kentucky Route Zero
Binary Domain
The Legend of Heroes: Trails in the Sky
Don't Starve: Reign of Giants DLC
Winter Voices series
The Cave
Nuclear Throne
Ziggurat
Alien: Isolation
Divinity: Original Sin
DuckTales; Remastered
Albion
Lichdom: Battlemage
Middle-earth: Shadow of Mordor
Halfway
The Testament of Sherlock Holmes
Witcher 3
Legend of Kyrandia II : Hand of Fate (moreso than the other games in the series)
Lands of Lore 1+2
Populous: The Beggining
Loom
Zak McKracken and the Alien Mindbenders
The Dig
Endless Legend
Also, fell free to check my messy, bloated and hardly mantained and [url=https://www.gog.com/u/Badseeder/wishlist]GOG wishlists

I'll consider offers of games not listed here too, but I may have them already (if they were dirt cheap at some point in time) or not be interested. On the other hand, I have no problem in trading multiples for one game if it is something I'd really like to have. Bolded games are the ones I'm looking for the most, and the ones that I'm more likely to trade for multiples, but that's not always necessarily the case.

Sucessfully traded before with Dedlago, Acidflux, Vipp, Ghorpm, HypersomniacLive ,Expopower, Ingsoc85(x3) Impaler26(x2), stg83, rodrolliv, Rolodzeo, Giltonnam, Accatone, samlii, Madmate and BranjoHello, Heretic777, shadowrgog, DynaEr, X-Com,apehater, Jamiecol90, Getcomposted, the.kuribo(x3), Catshade (x2), plan99, girolamocastaldo, Spectrum_Legacy, DeMignon, Deathjet, qalpha, PainOfSalvation and Sasuke12, Koreabeat.