From time to time, games presented in gog's catalog disappear. And thus Im about to ask - are the any criteria, based on which gog decide to take down some already presented entries?
I mean - there are really, REALLY lots of abandonware entries that received updates elsewhere but not on gog. And, I believe, most of them never get delisted for gog-only-knows reasons. Luftrausers didnt get the latest version for years, Don't Starve is not only missing like last 2 years of updates, but also the latest DLC, Not a Hero miss dlc campaign, etc etc. Not to mention lots of games that feature linux port elsewhere, but never received it there.

I believe, most of delisting happens because of direct requests from copyright holders, who didnt solve their issues with publishers. But also there probably should be some mechanism to force lazy devs/publishers to update their damn games or go away, no?

There is no such thing as abandonware.

Yes, gog remove games for many reasons, and you would need them to be specific if you want to know. Rights issues, contract issues, not adhering to drm free, failure to update, etc.

They will only get what the dev or publisher provide them, so if something is missing then port of call one is dev or publisher to find out why.

I believe, based upon observations of the various removals, that there's not a generic set of criteria that decides who is the weakest link and needs to say goodbye.

As for the whole update shenanigans, GOG apparently has a legal clause in their contract requiring developers to update their games soon after Steam, but:

1) They don't seem to always enforce it
2) This clause apparently makes some developers not want to bring their games here