jonridan: Windows XP is still around? Daaaaaaaaaaaamn... I know some of it's users don't like Vista, or 7, or 8, and 10... But to still keep on using an OS from 2001? I understand if you need for a very specific piece of software, but that only goes so far. Is like running a business with no telephone number or email. If it's not for business' reasons, then there is no excuse to being so obsolete. Get a Windows XP like distro, get a Mac (older models are not that expensive and are more supported than Windows XP), or just get Windows 7 (the lesser evil of the MS OSs of today). Gaming is too related to technology going forward, you can keep your old PC for the specific games that don't run well today, but you can't expect companies to keep supporting Windows XP (yes, even GOG... the idea is to make games work in current OSs, not support old ones).
Just my two cents.
TrueDosGamer: I think you're confusing age with obsolesce. For Apple Macs I'll have to agree you just can't use an older Mac Model as they force it that a newer OS won't install. Then the web browser's won't upgrade because your OS is too ancient.
Now the case of XP it can be installed even on a relatively modern machine such as Ivy Bridge 2012 and runs fine on it without issue. Step forward to 2018 almost 2019 I'm running XP even on the latest Intel i9-9900K octacore. XP's amazingly fast already on a quadcore but a Coffee Lake octacore it's like a Lamborghini engine in a 69 Vette or if you want inside K.I.T.T.
Next pop in a nVidia Titan X 12GB video card and you can pretty much play any XP game like it was on crack. But aside from that why not go further and make it XP, Windows 7, and Windows 10 all on one system and get the best of all three Worlds? That's what I do. No one builds a system for just one OS do they? If that's what you're doing then you're severely limiting yourself and need to step it up.
What is it you're worried can't be done in XP? I'm not quite sure how your business with no telephone number or email analogy comes from. Firefox up to v52.9 still works fine on Youtube videos in 1080P and 4K and every site including GOG here works except for the glitchy freebie issue I encountered that got fixed just using Opera. Plenty of video and sound cards around that work and network cards aplenty can be bought on eBay or Amazon even today. USB 3.0 cards also exist. You just have to know where and what to look for which isn't hard. In 2 more years XP will officially become the first retro OS to hit 20 and still be usable in the modern day and on modern machines. Life is Great. One day they'll try to kill Windows 7 support on Steam and make it Windows 10 only. The only reason they haven't is because they have to kill off the older ones first. But if XP support removal was never a consideration they wouldn't even consider touching Windows 7 and getting rid of it. But with no revolt that's how they get you sooner and Windows 7 is next on the chopping block now.
I agree there's no harm in making a game work in a newer OS. But often times you'll find that the game made for XP will run best natively on XP and much faster, less glitchier, and without compatibility issues. In some cases it just might be too incompatible to run in Windows 10 or just too buggy even if they managed it somehow that it is unplayable. Or maybe the game developers no longer have the source code so it can't be recompiled and optimized for Windows 10 and that'll be the best experience you'll get. So choose the best experience on an i9-9900K octacore in XP or a possibly buggy one in Windows 10 which might even run laggier. Which one would you prefer?
That's my nickel.
Regarding the telephone and email, it was just an example of "not getting with the times".
As for XP, specifically, there is Direct X, new APIs, DLLs, and security holes in the OS structure that can't be (or MS doesn't want them to be) fixed. So yes, the OS is obsolete. You can do a lot of things on XP, even today, but it is not as secure or efficient as a newer OS like Windows 7. And 20 years in technology is light years. Just because a car from 1941 still works doesn't mean is suitable for everyday driving. Yes, XP was built like a tank, and that's the reason even today it really does work, but there are things it wasn't supposed to do, and some of those things were "added" later like a sort of Frankestein's monster of updates and added new security holes. I would love to go back to Windows XP, but half the software I use doesn't even work there. If the companies that make software don't support that OS (unless you use older version of their software which they no longer provide support for) then you can't realistically keep on using it. I'm not against having an XP installation, like you said, multiple OS is a normal thing, but if that's the case then you can just use it for what it works and what doesn't work you just use the other OS... there wouldn't be people asking for stuff on XP. I am talking about people using only XP here. And like a previouse chart showed, almost no one still uses XP (or 8/8.1 by the way). Both of those OSs should be just removed from support by any company and use those freed assets to improve support on the OS most people use (7, 10 and freaking Linux... yes, Linux has more users than XP and 8/8.1... at least on Steam). Smaller companies can't keep support for that many OS and they have to draw the line somewhere... a 20 years old OS seems like a nice place to do it. We are talking about an OS that, at least in my country is old enough to drink, drive, work and live on it's own. Is a freaking lifetime.
Age sometimes IS obsolecence. Actually, with technology, most of the time it is.