... what do you think?

Seriously... while I appreciate you asking that here instead of making a giveaway straight off the bat... really?!

Buy a steam game

Hey people, let's create shit loads of private giveaways so it'll buy steam games automatically, and we'll have infinite steam games!

What is stopping people from creating bots to spam games if somehow the magical fairies decided to pay for every listing that's created on this site?

You have to own a gift copy of the game to gift to someone when your gift giveaway ends on steamgifts.

Gift.

You can buy the game before the end of giveaway, then give it to the winner.

an unused steam key is ok, isn't it?

What is it?

I think that is the explanation of all fake giveaways.

LOOOOOL..... You have to buy the game, make a giveaway and then give it from your inventory. Use your logics tho....how could SG buy HIB's when they're not even sold anymore...

reading the faq is a good idea

This is a great example of how fake giveaways makers think, that the site automatically buys the game of their choice when you make one and gives it to them, infinite steam games.. really?

You, good sir, are a moron.

It's not by telling this guy he's a moron that we'll make things change.
Therefore to answer your question FrigginTiiX: you can create a giveaway for any game from the list. When it's over, you'll have to contact the winner and give them the game manually - normally I think you need to add them to your friends list and gift it.

Keep in mind you can create a giveaway without actually having the game in your inventory. You will need to get the game sooner or later - otherwise this could result in your account being banned from Steamgifts.
Also, SteamGifts is in no way associated with Valve or Steam, so for future references don't expect Valve to sign any sort of partnership (such as buying the game automatically) unless there's something on the forums straight from SG's team.