Buy it.

You buy the game...

Er... you'd most likely have to email the key or directly add them on steam and make sure they actually get the key.

You're supposed to HAVE the key, not craft it with magic.

If you do not own the game or the key delete the giveaway(s) right now.

You cannot giveaway games from your steam library.

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bought the game for yourself, what you activated can not be given away, either buy it again so it sits in your steam INVENTORY (not library) or delete the giveaways

How? Do you have it in your library? If so, then you can't give it.
Do you have it in your inventory? Then just give it.
Do you have it as a string XXXX-XXX... Then just give that.

You can not make a key out of a game!

You can gift it through steam as long as you bought it as a gift.

not if you used it and put it in your library. if you bought as a gift(steam inventory) or have something that looks like 3AT4R-345FT-NE4LC then yes
(codes fake don't bother ninjas. I just typed letters)