I can offer some of the following for one key-
Tradeable:
- Serious Sam Classic: The Second Encounter
Keys:
- Fortix
- Ravaged: Zombie Apocalypse
- Tower Wars
- Zeno Clash
- The Whispered World
- Alien Shooter
- Alien Shooter 2: Conscription
- Alien Shooter 2: Reloaded
- Zombie Shooter
- Zombie Shooter 2
- Yumsters 2: Around the World
- Serious Sam HD: The First Encounter
- Serious Sam HD: The Second Encounter
- Dead Space
- Medal of Honor
- Command & Conquer: Red Alert 3 - Uprising
- Chains
- Hydrophobia: Prophecy
- Nightsky
- Fractal: Make Blooms Not War
Serious Sam 2 - 1 key
McPixel - 1 key
DLC Quest - 1 key
The Binding of Isaac - 1 key
Just Cause - 1 key
Sid Meier's Civilization V - 2 keys
BioShock - 2 keys
Bioshock 2 - 2 keys
Super Meat Boy - 2 keys
Garry's Mod - 2 keys
Titan Quest Gold - 2 keys
Red Faction Guerrilla - 2 keys
Postal 2 Complete - 2 keys
Just Cause 2 - 2 keys
Renegade Ops - 2 keys
Half-Life 2 - 2 keys
Rock of Ages - 2 keys
Forge - Starter Pack - 2 keys
Syberia Bundle - 2 keys
Audiosurf - 2 keys
Bastion - 2 keys
Magicka - 2 keys
Fairy Bloom Freesia: 1 TF2 key
Exceed Trilogy: 1 TF2 key
Afterfall InSanity Extended Edition: 1 TF2 key
All tradable gifts:
Damnation - 2 keys
Command & Conquer: Tiberium Wars + Kane's Wrath - 4 keys
Alien Breed™ Trilogy(3 games: Alien Breed 2: Assault + Alien Breed 3: Descent + Alien Breed: Impact) - 2 keys
Alan Wake Franchise(Alan Wake's American Nightmare, Alan Wake, Alan Wake Collector's Edition Extras) - 3 keys
Painkiller: Hell and Damnation - 2 keys
Deus Ex: Human Revolution + Tactical Enhancement + Explosive Mission Bundle - 3 keys
Forge - 1 key
ArcaniA: Fall of Setarrif and ArcaniA Gothic 4 - 4 keys
Two Worlds II + Two Worlds II - Pirates of the Flying Fortress - 3 keys
Tropico 4 Collector's Bundle(+ all dlc) - 4 keys
DiRT 3 - 4 keys
Battlefield Bad Company 2 - 4 keys
Dungeon Siege Complete(all D.Siege games) - 3 keys
Binary Domain - 3 keys
Portal pack(Portal, Portal 2) - 4 keys
Endless Space - Emperor Edition - 4 keys
Sanctum - 1 keys
Flatout Complete Pack(FlatOut, FlatOut 2™, Flatout 3: Chaos & Destruction, FlatOut: Ultimate Carnage) - 4 keys
Hitman: Absolution - 6 keys
Killing Floor - 2 keys
Left 4 Dead 2 - 4 keys
Serious Sam 3: BFE - 3 keys, (2 copy of Serious Sam 3: BFE - 5 keys)
Nuclear Dawn - 1 key
Titan Quest + Titan Quest - Immortal Throne - 3 keys
The First Templar - Steam Special Edition - 3 keys
Dungeons Gold(DUNGEONS - Steam Special Edition, Dungeons - The Dark Lord, Dungeons: Into the Dark DLC Pack, Dungeons: Map Pack DLC) - 3 keys
Trine 2: Complete Story - 2 keys
Trine Franchise(Trine, Trine 2: Complete Story) - 3 keys
F.E.A.R. 3 - 3 keys
Resident Evil 5 - 3 keys
Deus Ex Collection(Deus Ex: Game of the Year Edition, Deus Ex: Human Revolution™ - Explosive Mission Pack, Deus Ex: Human Revolution™ - Tactical Enhancement Pack, Deus Ex: Human Revolution™, Deus Ex: Human Revolution™ – The Missing Link, Deus Ex: Invisible War) - 4 keys
Devil May Cry 4 - 3 keys
Sniper Elite: Nazi Zombie Army - 3 keys
Batman: Arkham City - Game of the Year Edition - 4 keys
Darksiders II + Darksiders II - Season Pass(total sale price 16$) - 6 keys
Natural Selection 2 - 4 keys
Chivalry: Medieval Warfare - 4 keys
Torchlight II - 4 keys
Dead Island GOTY - 3 keys
Worms Ultimate Mayhem - Deluxe Edition - 3 keys
XCOM: Enemy Unknown + Both DLC - 6 keys
Ace Combat Assault Horizon - Enhanced Edition - 4 keys
Sins of a Solar Empire: Rebellion - 4 keys
Magicka - 2 keys
Worms Revolution - 2 keys
FUEL - 2 keys
S.T.A.L.K.E.R.: Clear Sky - 2 keys
Command & Conquer 4: Tiberian Twilight - 3 keys
Red Faction: Armageddon - 2 keys
NBA2K13 - 4 keys
The Elder Scrolls IV: Oblivion® Game of the Year Edition Deluxe - 4 keys
Guns of Icarus Online Collectors Edition - 3 keys
Rome: Total War Gold Edition - 1 keys
Command & Conquer 3: Tiberium Wars - 3 keys
Brutal Legend - 3 keys
Sanctum 2 - 3 keys
Medal of Honor 2010 gift - 3 keys
Lord of the Rings: War in the North - 3 keys
ORION: Dino Horde - 2 keys
Age of Empires® III: Complete Collection - 5 keys
Risen 2: Dark Waters Gold Edition(Risen 2: Dark Waters, Risen 2: Dark Waters - A Pirate's Clothes DLC, Risen 2: Dark Waters - Air Temple DLC, Risen 2: Dark Waters - Treasure Isle DLC) - 3 keys
Sonic & All-Stars Racing Transformed - 2 keys
Port Royale 3 Pre-Order Gift - 2 keys
RollerCoaster Tycoon® 3: Platinum - 2 keys
The Showdown Effect Digital Deluxe(Includes The Showdown Effect + Magicka gift) - 2 keys
Dead Space 2 - 2 keys
Dead Island Riptide - 5 keys
Street Fighter X Tekken - 4 keys
BioShock 2 - 2 keys, BioShock 2: Minerva’s Den - 1 key
Civilization V - 2 keys
Show me what you can do
Update: got two keys.