Those are usually games that were given away for free in huge quantities, so they get removed from the list to prevent people exploiting it by getting multiple keys and giving them away here to get CV. Typically they get given away in the forum, for example make a thread where, if a person had it on their wishlist before the thread was made, they can ask for it. For games most people already have or don't really want, you can make it first come, first serve, for more desired ones you can make a list of people who want it, then use a random number generator to pick a winner.

If a game doesn't appear in the list it is likely because it has been given away for free in large quantities and therefore you cannot make a giveaway for such a game. If you make a giveaway using a different game then it is a misleading giveaway and is also not allowed. I'd advise reading the FAQ, Guidelines and Terms of Service for more information regarding creating giveaway and how to use the site.

Thank you. :)

Thank you. I already have a complex over the mysterious blacklist I somehow found my way on, yesterday. XD

And you, too. :)