Gede: Hello. Also new here. Here is something I haven't understood.
Am I correct in thinking of the giveaways as new games that are purchased for that (or other) purpose or as game codes that have not yet been redeemed (like the Witcher 2 stamp collection)?
Is trading the same? I have not found a way to "re-own" a game in my collection (that is, convert it into a code to transfer its ownership to someone else), even if I have never downloaded it yet. I tend to thik it is not possible at all.
That would mean that the games are in my collection
permanently, and that the only way to transfer them to someone else would be to give them my entire account. I'm not sure if the ToS allows this, but I think I can always leave it for my kids to inherit (and ignore it) some day --- fortunately there is no DRM to prevent this.
Hi! Welcome! I know that your questions have pretty much been answered, but thought I'd quickly make a post of my own. :p
Well, I guess in a way, it's both. Giveaway games often are purchased for the sole purpose of 'giving it away'. When you purchase a new game, whether you own it already or not, you'll have the option to 'gift it'.
See
THIS IMAGE!
For the purposes of this, I have added Arcanum to my cart. On the right, you can see I ticked the box that says "gift this order". You could then add an email and send it off to whoever you want. Often people also send this to their own email though, where they get a code for it, which they can then PM someone to redeem.
Also, If you already own a game that you purchase, because it already exists in your library, GOG will send you an email with a code, that you can then gift to someone else.
Very often though, people do use unredeemed codes, like the Witcher 2 code for giveaways, especially if they already own said game. Giveaways are not confined to GOG games, so you'll also see plenty of giveaways with Steam keys, Desura, etc.
As others have already said, there is no specific 'trading system' built into GOG. It's purely run by users. When trading, you also use the same 'gifting process' as above, but now you obviously expect a code/gift in return.
It is not possible to 'transfer ownership' to someone else. If you want to keep your copy of the game while still giving a copy to someone, you'd need to buy them a separate copy, or be satisfied with just giving them the files in person/access to your account, or something.
As HunchBluntley said though, if you don't want a copy of the game, assuming you haven't downloaded anything yet, support will let you remove the game from your account and get a gifting code instead.
Gede: I purchased a bundle that included some games I already own, and wanted to know if I could gift them (either in a giveaway or privatly to a friend).
If you already own some of the games, you should be able to gift those. :)
Anyway, I hope that all helps!