I (might) have multiple copies of each:

Steam Games:

Gifts:

Contraption Maker
Counter-Strike: Source - Guest Pass (SA/LATAM only)
Dead Island: Epidemic (delisted)
Dino D-Day (SA/LATAM only)
Gun Monkeys (delisted)
Ibb & Obb (SA/LATAM only)
Rise of The Triad (SA/LATAM only)
Sanctum
Space Farmers
SSHDFE (Serious Sam HD: the First Encounter + Serious Sam Fusion)
Super Hexagon (SA/LATAM only)
Super Monday Night Combat (delisted)
The Ship - 2 Pack Gift

CD-Keys:

16-bit Trader
3D Pool
A New Beginning - Final Cut
A Sceptic's Guide to Magic
Age of Wonders 3
Agent Awesome
Alchemist
Beat Me!
Black Salt Coreuption
Blackguards - Standard Edition
Bless Unleashed (beta)
Blood of Steel (beta)
Broadsword : Age of Chivalry (delisted)
Bone Collection (Bone: Out from Boneville + Bone: The Great Cow Race) (delisted)
Brawl of Ages (beta)
Broadsword : Age of Chivalry (delisted)
Chains
Choose Wisely
Cultures - 8th Wonder of The World
Darksburg (beta)
Decay: The Mare
Deponia - full version
Disintegration (may keep)
Double Cross
Dragon's Dungeon: Awakening
Earth 2140
Earth 2150 Trilogy
Earth Atlantis
Enclave - Gold
Evergarden
Extreme Racing on Highway
Fall of Light
Fortified
Fractured Lands
Global Adventures (beta)
Gold Rush! Classic
Gomo
Gorky 17 (aka ODIUM)
Guns of Icarus Alliance
Haimrik
Heli Heroes
Holy Potatoes! A Weapon Shop!?
House of 1000 Doors: Evil Inside
HyperBrawl Tournament
Jack Orlando: Director's Cut
Journey of A Roach
Ken Follett's The Pillars of The Earth
Knight Shift
Knights and Merchants
LifeSpawn
MARS OR DIE!
Millennium 3 - Cry Wolf
Monster Slayers
Moonchild
Mortal Royale (beta)
Moss Destruction
MotoGP 15
My Big Sister
NAKARA: Bladepoint - Test Server
Opaline
Pinball Arcade
Pixel Puzzles: UndeadZ
Planets under Attack
Red Risk
Regions of Ruin
Renowned Explorerd: International Society
Sanctum
Satellite Reign
Septerra Core
Serial Cleaner
Serious Sam 2
Serious Sam 3: Gold Edition
Serious Sam Fusion
Serious Sam HD: The First Encounter
Serious Sam HD: The Second Encounter
Skyhill
Soul Shards (beta)
Star Wolves 2
Super Inefficient Golf
Syberia II
The Franz Kafka Videogame
The King's Bird
The Lost Dungeon Of Knight
Theater of War
Throne - Death Merchants
Trident's Wake
Undefeated
Vagrant Hearts 2
Valhalla Hills
War identity
When Ski Lifts Go Wrong
World War I

XBOX Games:

Halo 5: Guardians
Halo: Master Chief Collection
Game Pass for PC - 14 DaysZombie Buster Rising

PlayStation Games:

Symbols in the Stars Dynamic Theme (PS4)

GOG Games:

The Witcher: Enhanced Edition (GOG)
The Witcher 3: Game of The Year Edition (GOG)
The Witcher 3 - %70 OFF coupon (GOG)

EGS / Epic Games:

Startup Panic

Microsoft Store Games:

Dead by Daylight: Curtain Call & Pulcinella DLC

GFWL (Games for Windows - LIVE):

Battlestations: Pacific
Batman: Arkham Asylum
BioShock 2
Blazblue Calamity Trigger
Grand Theft Auto IV
Grand Theft Auto IV - Episodes From Liberty City
Gears of War
Fallout 3
Fallout 3: Game Of The Year Edition
FlatOut: Ultimate Carnage
FUEL
Hour of Victory
Halo 2
Juiced 2: Hot Import Nights
Kane & Lynch: Dead Men
Legend of the Galactic Heroes
Lost planet colonies edition
Quantum of Solace
Red Faction: Guerrilla
Resident Evil 5
ShadowRun
Star Wars: The Clone Wars - Republic Heroes
Stormrise
Street Fighter IV
The Club
Vancouver 2010
Viva Pinata
Warhammer 40,000: Dawn of War II
Warhammer 40,000: Dawn of War II Chaos Rising

Steam DLCs:

Assetto Corsa - Ferrari Hublot Esports Series Pack
Battle for the Galaxy - Ice Bastion Pack
Battlerite - Armored Black Bear
Crusader Kings II: The Old Gods
Fall Guys - Dragon Hugger Costume Pack / Dragon Hugger Pack
Friday the 13th: Killer Puzzle - Super Slasher Pack
Heavy Metal Machines: Giveaway Pack Season 6
Idle Champions of The Forgotten Realms - Celest's Starter Pack
Idle Champions of The Forgotten Realms - Starter Pack
Quake Champions Bundle (500 Platinum + In-game Items)
RISK: Global Domination European Conquest
Shadow warrior 2 - Alienware DLC

Other DLCs:

Black Desert Online Lauren Family Gift Box
Dauntless SteelSeries Sigil and Flare - ٍEpic
Fractured Lands - Conspiracy Theory Dustrider Paint Job
GWENT - Starter Pack (GOG)
GWENT - Kegs (GOG)
Quake Champions Bundle (500 Platinum + In-game Items)
Spellbreak Sundowner Outfit (EPIC)
The Elder Scrolls Legends - Moons of Elsweyr expansion
Warframe Booster Pack (All Platforms)

Accounts:

DRIVER: San Francisco - Uplay Account

Coupons:

The Witcher 3 - %70 OFF coupon (GOG)
CD Project Red merch - %25 OFF coupon

Others:

TF2 Keys
ToD
Gems