True, but the original Steam was created for managing updates to Counter Strike and their anti-cheap system (VAC if memory serves me right). Also back when having a low WON ID (now SteamID) was a badge of honor (like having a low Slashdot account ID).

Sorry for the useless comment but I really like the idea of a „anti-cheap system“.

I will use it in my next presentation for shareholders. /s

I'm sure the behavioral economics people at Activision and EA trying to get kids to buy more cosmetics would have a lot to say about that...

Yeah, still feels like even today Steam could pop up something in this style somewhere when you press a less common button or cause a less common error. Kind of like how Windows would occasionally have even Windows 3.x style dialogs up until last year in Windows 11, and still has a few stragglers from Windows 9x era.

Yes, the Steam client was originally built on top of the same VGUI library used in Valve's games, and used the same style as HL1/CS/etc back then.

Was VGUI built on GTK back then? It looked exactly the same as other GTK apps I was using in the early 00s.

Not sure - the VGUI code in the Half-Life SDK was a bunch of header files and a .lib file but I'm not sure what actually implemented it. Back in the early 2000s I assume it was either Windows-specific or rendered using DirectX/OpenGL.

It was added to Half-Life (and not long after to Counter-Strike) in March 2000 or so. Not sure when Steam first launched but I think there was a beta from 2002?