Currently IGDB seems to rely on ISO 3166-1 for regions, which is an easy source to add all current regions, and then rely on ISO 3166-3 for historical region such as "East Germany [DDDE]".

But currently there's an issue where IGDB uses "NA" (Namibia) for North America, "AS" (American Samoa) for Asia and "WW" (unassigned, but not private use) for Worldwide. These three codes have to change, and I suggest using UN M49. You would then use code "003" for Northern America (excludes Central America and the Carribean), "142" for Asia and "001" for Worldwide. But I understand if this would be hard to change, and arguably Namibia and American Samoa aren't going to be relevant, and there's likely not going to be a country with the code WW anytime soon. However, still a good practice not misusing ISO 3166-1.

However, this should not cause any issues adding popular regions like Russia [RU], Sweden [SE], United Kingdom [GB], France [FR] and so on without any collissions. As of now, I'd like to add Swedish, German, Polish and Russian localisation with covers and titles.

bump, add all regions

Other regions that should be added is every single country, honestly. Because releases are different even within Europe, and this is also very useful when adding localised content such as titles and covers.

Another example: https://www.igdb.com/games/reborn-online, which is currently only released in Russia, but not worldwide.

Source: https://mmo13.ru/games/reborn

+1

Example: https://www.igdb.com/games/besieger/ was released in Russia on 2004-04-21 and worldwide on 2004-05-28, but I can't specify that the first release was only in Russia.