I've just got this "up two" thing recently (it had been "up one" till yesterday) and I have no idea what it means. Anyone knows?

I've never seen that before. Is this through Galaxy, or just the browser? Maybe it means that 2 of your games got updated.

Nothing like that in my view of the pages. I even tried to inspect that area and there are no extra HTML elements for me.

Have you tried right-clicking (secondary-click) on that arrow and number, and then choosing "Inspect" or a similar option? That would reveal the HTML for it in another window, and then you would have some more clues.

Like I said, I don't have that arrow and number, and when I inspected the area I didn't find anything hidden. So it's probably not being included for everyone. You're in a better position to inspect it yourself because you actually have that showing, and then can tell us more.

EDIT: Also, you could try just hovering the pointer over it for a few seconds and see if a popup message appears somewhere, like next to the pointer or maybe at the bottom of window. It might describe it or maybe reveal a link to another page.

Which another thing, does the pointer change when hovering over it? Does it seem like a link? Maybe try clicking it then and find out what page it goes to.

Thanks for all your helps! Yeah, now I believe it's an indicator for updates, since I do have 3 updates to my games at this moment (and it's "up 3" now), and inspecting it shows something like this:
<span id="menuUsername" class="menu-username" ng-bind="account.username" data-be-updates="3">Makotolia</span>

And I'm really sorry that I forgot to say that I'm using Barefoot Essentials. I also suspected it was some feature of it ('cuz I didn't see it when using my iPad), but I just forgot to describe it in OP...

Problem solved. Just the browser, and yes, now I believe it is the update indicator. It seems that you really are good at various kinds of puzzles, matey ;)

I'm using Win XP, so Galaxy is actually not an available option for me.

Now I believe it's a feature of Barefoot Essentials showing the updates to my games, thus not everyone has it shown.

I really want to thank you, your approaches to solve this question is inspiring!

Grargar was definitely on the money. :-) I don't use any web browser extensions and keep forgetting about the special ones for GOG.

Barefoot Essentials and Adelia's Fundamentals do have many features, so I keep hearing. It might be nice if they showed a logo somewhere, like maybe bottom left corner (in a fixed position), as a reminder they are installed and active. That could even be made as a button for a quick way to temporarily toggle their effects on/off for discerning what's different from the normal website, or any unexpected conflicts of having both installed.

It was rather exciting that there might have been an unknown feature of the GOG website, but still interesting that it's provided by one of the extensions instead.

Yeah, a button could be helpful. Maybe you should suggest it in that thread ;)

It has been added to Barefoot Essentials when the GOG update flags did not work at all. You can achieve this pretty easy. Those extensions only work by installing a program managing those (Greasemonkey or Tampermonkey i.e.). Disable this program (it's just one checkbox) and you are back to pure GOG again. You can also disable just one or two scripts this way. I did this multiple times to find out if a bug I experienced was caused by GOG or by one of the scripts. You will also see if Barefoot Esentials or Adalia Fundamentals are installed in your browser by clicking the "about" menu. Here you will see the scripts installed because here you can also access the settings of them. A button or icon indicating if the are installed is imo unnecessary and I would not want to see this at all.