Age of Wonders 3 localization

https://steamdb.info/app/226840/subs/

Region restrictions are going to be related to your own region [or in the case of Gifts purchased through Steam, your currency], so it's always important to include that information with queries of this sort (in your case, it's visible through your Steam profile, but it's still polite to mention it regardless).

Glancing at SteamDB, the only region-restricted copies of AoWIII are the RU/CIS and RU/CIS/EU labeled ones, which lock those keys to the associated regions. This appears to be one-directional, as well, as the ROW, PL, HU, etc copies don't appear to have any limitations set [as far as excluding RU/CIS/EU regions]; Thus, if you're not within any of the regions listed, your key is theoretically assured to not have any restrictions.

As you appear to be in the US, I don't imagine you'd have any region restrictions to worry about.

Do note that SteamGifts Deals threads are always very on top of any associated region restrictions, so if this is in regards to the free Humble key, all you'd need to do is check against the original post of that thread [assuming it's a sensualshakti thread] or the comments of that thread [if, as an unusual occurance, it isn't]. If this (inexplicably) is related to a gift purchased through Steam, the Euro seems to be the only currency that an individual purchasing with USD would be unable to gift toward.

Thank you for the very detailed reply. It was really informative and helpful.
I will keep my eye on that thread in the future.

I tend to use https://steamlocked.com/ to check restrictions. I'm not sure if it's as reliable as steamdb.info, but it's easier to read. It probably pulls the information from steamdb.

https://steamlocked.com/app/226840

I seem not to know the step of Identifying the App ID. And also Sub ID. Any hints on that?