Giving Another Person's Game Away

have your friend trade you the game or gift it and add it to your inventory instead of redeeming, then its basically yours which will allow you to do a giveaway for it.

trade it?

As long as the winner gets it it should be fine :)

Get his gift through the trade system, then do the giveaway yourself.

Okay, am I missing something here? People are saying get it through the trade system, but like I said, I haven't been able to receive it because I already own Civ V.

Is there something other than gifting that you're referring to?

You just can do the giveaway and then your friend send it to the winner since he is fine giving it away. Potaeto potato...

trade ftw

But wouldn't it be you getting contributor value?

Using other people's games to give yourself contributor value = no go

They could also view this as "account sharing" which is also not allowed.

"I asked my friend to just gift me his copy of Civ V so I could do another giveaway here, but I guess Steam won't let you receive a gift if you already own the game."

-> You can have as many gift of a particular game as you want in your inventory, even if you own that game in your library, there are no restriction's on that. However, you can't redeem that gift by yourself ofc, as you already have it in your library.

So, you can ask your friend to gift the game to you via steam's trading window or send it as a gift to you, So that you can create a giveaway for that particular game here on Steam Gifts.