What Constitutes a Free Game?

https://www.steamgifts.com/discussion/pJRbR/can-we-have-a-list-of-games-that-cannot-be-created-as-giveaway-unofficial-list-inside/search?page=12

once given for free in large enough amounts, the game will always be considered free on SG to prevent exploiters from just "waiting it out"

free also includes games that had price glitches where it was sold for over 95(?)% off the base price.
so this includes regions with constant price reductions such as russians from buying cheap stuff and giving it away here for "CV"

They are considering allowing free game GA's, no update afaik since the holiday announcement:

https://www.steamgifts.com/discussion/Ot9wk/happy-holidays

It looks like pretty much anything that is a several thousand keys drop that was not on this site. There are a few exceptions, like the two or three times Steam had an "add this game to your library in the next x hours and you can keep it" events, since those were not regiftable in any way.

I can give you an example, Syberia was given away for free some months ago and is considered not giftable. Usually almost anything you can get for free on a mass giveaway is considered not giftable from that moment on.

As a side note that wasn't mentioned yet in this thread, games that aren't allowed to be given away will not appear in the giveaways list, unless it hasn't been added by the mods yet. So if a game was free a long time ago but you aren't sure if it can still be given away, try typing the title in the giveaways creation page and if the game doesn't show up - you can't give it away.

if you got a game from a promotion like gleam or indiegala, then it will be disabled here.
except for tremorgames freebies because people invest their time in farming coins.