I explicitly left out the Interplay mentions (for the most part) because the situation is not that clear. Some mentioned have Mac/Linux builds. I need more information, are these more recent builds, or what's the difference?
I think either some of those Mac/Linux ports might have already been on GOG but not on Steam at the time of the tweet
or they were added some time between the tweet and today. I checked SteamDB and ALL of the games mentioned have both Mac and Linux builds on Steam. The situation with GOG is a bit more complicated (according to the store pages): Conquest of the New World
: Missing Mac/Linux build Cyberia 2: Resurrection
: Missing Mac build Descent
: Missing Linux build Descent 2
: Missing Mac/Linux build Dragon Wars
: Missing Mac build Earthworm Jim 1+2: The Whole Can 'O Worms
: Missing Mac build Kingdom: The Far Reaches
: Missing Mac/Linux build Lost Eden
: Missing Mac build M.A.X. + M.A.X. 2
: Missing Linux build Prehistorik 1+2
: Missing Mac build Redneck Rampage Collection
: Missing Linux build Screamer
: Missing Linux build Screamer 2
: Missing Linux build Shattered Steel
: Missing Mac/Linux build Stonekeep
: Missing Mac/Linux build Subwar 2050 Complete
: Missing Linux build
So I have no idea whether the Mac/Linux builds on Steam are newer, but it's clear that GOG doesn't have some of them at all.
Are we sure about Cardaclysm being on the list for missing updates? The list notes say it's missing updates since March, but gogdb says it's updated well past that and the last posted changelog on Steam
You're right, according to GOGDB, the last two updates were on 9 March 2021 and on 26 July 2021. Last update on Steam was on 22 July 2021. I think the game might be up-to-date. It was probably reported some time after the last March update and then nobody noticed that the game was updated again in July.