1999 games...i have got 4 Tf2keys to spend...¿My game number 2000?. Help me!.

The subtitle-less Prince of Persia would be my suggestion, not sure if you're looking for actual trade offers or just suggestions though.
(The game has no uPlay)

The Wolf Among Us (as I've seen other TellTale games in your library)

Heroes of Might and Magic V Gold, nuff' said.

Might I recommend Gothic 3? It's the final PiranhaBytes developed entry in the series, and catalyst for the production of the Risen franchise, arguably the least appreciated by Gothic enthusiasts yet also my personal favorite. An open-world RPG with some grim tones, a subtly challenging combat system (I would recommend you acquire the community mod to prevent being stunlocked) and literal days worth of exploration. It, along with the rest of the Gothic series, is on sale throughout the weekend.

EDIT: All pertinent patches are available at World of Gothic.

EDIT II: Also, whether you select this game or another, might I offer my congratulations on the landmark? That's quite the collection, mate.

Wanted to suggest the Fully Loaded bundle, checked your profile, saw you already owned it.

maybe I'll come up with something else :P

This guy has Saints Row IV for 4 keys.

Coma:Mortuary cheap game ^^

Wait for GTAV price to drop,
exchange keys for GTAV,
PROFIT

:D

Life is Strange or maybe Fahrenheit :P

Metal Slug X ?

I see that you haven't experienced the wonders of Sakura Spirits and Sakura Angels. Both should be about 2 keys each, so you can treat yourself to amazing plot that will cause you to finish an entire box of tissues.

Crawl! Best game for friends! Or Broforce/Super Time Force Ultra

Heroes of Might and Magic III. I prefer the old one, but you can buy HD too.

You can get mount and blade : warband, which is a pretty cool game. also the dlc napoleonic wars, which you can get multiplayer servers with 200 max players. it's nice. you can also join a regiment and train and go to competitions if you are into that stuff.

Valkyria Chronicles, Anime War Simulation JRPG

http://store.steampowered.com/app/294860/

Fall of the New Age Premium Edition :P

When I first saw the title, I thought you meant games made in 1999. I'd suggest Fallout 3, one of the best games I ever played! Well, that is if you can get past the bugs and crashes.

Legacy of Kain

Maybe Far Cry 3? I see that You have the Blood Dragon but not the main game.

Aliens versus Predator Classic 2000

ps. i dont want the game.

clearly CSGO :D

My vote goes to Fallout: New Vegas, it's on your wishlist and you just might be able to shop around and leverage prices to get the UE for 4 TF2 keys, If nobody goes lower than 5 keys then go with Dark Souls :)

just my $.02

Assassin's Creed: 2 or Brotherhood in my opinion.

Starbound for 2 or 3 keys from russian trader :)

I suggest one of the great games from '97. It was golden age, most of them are enjoyable till now. Show your class and get game for oldboys! :D