An example. Well, here you have Daymare: 1998. Developed by Italians.

However, All in! Games SA. is one of its publishers. And this is a Polish company.
And I believe Destructive Creations is also a Polish company. But I'm not entirely sure. If I'm wrong, please correct me. That's why I don't think it's just Polish developers' games that are celebrated, but Polish publishers as well.

Congratulations to Poland and to GOG!

Yep, just check OP again (or read my response to Syphon72) ;)

In these nationality-themed sales, it's always like that. They might include games just because the rights happened to land with a company from that country, even if the games have nothing to do with it otherwise.

I am sorry. I have just checked the OP.
Many thanks and apologies once again. =)

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Since we're talking about Polish games (from developers and publishers), I'd like to ask about a game from 2005 called Bonez Adventures Tomb Of Fulaos. It's a game that combines action, adventure and role-playing. It's quite an entertaining title, to be honest. Will we ever see it in the GOG catalogue?

I remember the publisher as being PLAY, or at least that is the name I recall. The developer was called Bone Artz.

Victoria 2

Nice catch, but Mobygames says it's also published by Cenega Poland, so that's why it is prolly included too. ;)
https://www.mobygames.com/game/63460/victoria-ii-civil-war-edition/

Is Priest Simulator worth the time?