Okhlos got the Omega upgrade and was added to the GOGmix.

http://www.gog.com/mix/games_that_got_addtional_content_for_free_after_release

Do you update the description when a game already on the list receives more free content?

Sometimes I do, but there is a very scrict character limit for the descriptions. Will look into Darkest Dungeons to see, if it makes sense to change the description. I guess you are asking because of that game.

Yes, that's the game that prompted me. Since the game's already on the list; we're good; no need to fiddle with the description.

VA-11 Hall-A: Cyberpunk Bartender Action got a content update that included a prologue chapter, a special demo chapter and new wall designs.

The game was added to the GOGmix.

http://www.gog.com/mix/games_that_got_addtional_content_for_free_after_release

Thank you for reporting. I've edited my description and my rating to reflect that.

Mmmm...but DLCs does not come yet, and its offline installer also not updated.

The Curious Expedition got the Arctic Expanse update. Does it count?

Yes, of course. Will add it to the GOGmix tomorrow.

The Curious Expedition, Tales of Maj'Eyal and No Man's Sky were added to the GOGmix:

https://www.gog.com/mix/games_that_got_addtional_content_for_free_after_release?ccr=y

Hm, I can`t see Tales of much egal in the list, it should be between "Syndicate Plus" and "Terraria", but there is nothing!

It still was at the very end of the list (you have to sort the games manually when you create or edit a mix). Should be in the right position now.

Ah yeah!
Well, I noticed something else:
In some cases, games beginning with "The" are placed in the "T" section of the list, in other cases the "The" games are at the spot where they should be if you leave the "The" away and use the second word for determining the correct spot in the alphabetical list.
That`s a bit weirdo!

Think that was only The Real Texas. Should be at the right position now. Sorting the games really is a pain in the ass, because you can't drag them around, but instead have to do one click for every single position. Which means I have to click more than 100 times to move a game from the end to the top. I'm always happy when a game starts with S, T or U instead of A, B or C. ;-)

But weirdest thing about the mix is that the title say addtional instead of additional and no one can do anything about it.