I'm not sure if anyone's done this yet and I've been searching the forums. If there's a better list somewhere else please link below. Otherwise, I hope I can help guide people into knowing what works on what Windows ("officially" speaking). I originally thought up this idea due to some conflict I'd have with installation and compatibility, which I had to go out of my way to have work (I currently run off Windows 8). Not everyone is a computer genius, or even clever enough with knowing how to work around troubles that are annoying, and most of the time it's just unnecessary. That's why GOG exists in the first place; to make old games work on newer systems.

Below is a list I've compiled of every game that is not compatible with a given version of Windows. I start of with with games that don't work on Windows 8, and subsequently go down through Windows 7, Vista, and XP. You'll notice that more run on XP than even newer Windows, especially when it comes to 8.

PLEASE NOTE: Compatibility here is a relative term seeing that some games CAN run on versions of WIndows that are not on their game cards, for instance Battle Realms works on Windows 8, and there's a workaround for Empire Earth II as well (as I edit this posting, you'll see the edits next to the game title to mention any specific workarounds. Check out individual game forums and research the game(s) that interest you to see what problems exist, or inquire as to why they don't work before you purchase them). In this manner, "officially" is used in the context of GOG's information on any game's card regarding what system it works on and what systems it doesn't, but as stated some games can work, if tweaked a bit (or they just work, and their game cards don't reflect that compatibility).

The GOOD NEWS: Over 630 games work on newer systems, even if many of those are newer indie titles. If you ever find ways to run a classic game on Windows 8 or any other version below please at least submit the info to the forums here on GOG as it will help anyone else who may be curious. The more games people realize are compatible, the merrier :)

Also, if I'm omitting any titles or if I've made any errors please let me know.

I will periodically update this if it's necessary.

Games that are NOT "officially" on Windows 8 (but do run on XP, Vista, and 7) on their game cards:

1) Project Eden
2) Empire Earth 2 Gold
3) Deadlock 2: Shrine Wars
4) Populous: The Beginning
5) Septerra Core
6) Jagged Alliance 2
7) Jagged Alliance 2: Wildfire
8) Gabriel Knight 3
9) Alan Wake
10) Alan Wakes American Nightmare
11) Kings Quest 7+8
12) Betrayal at Krondor Pack
13) Return to Krondor
14) Might and Magic 9
15) MDK
16) SHOGO: Mobile Armor Division
17) Desperados
18) Independence War Deluxe
19) Darklands
20) Disciples 2 Gold
21) Zafehouse Diaries
22) Haegemonia Gold Edition
23) Tex Murphy 1+2
24) Lionheart
25) Rayman 3
26) Creatures Exodus
27) Creatures: The Albian Years
28) Realms of Arkania 1+2
29) Realms of Arkania 3
30) Patrician 3
31) Rogue Legacy
32) SWAT 3
33) Still Life
34) Gangsters: Organized Crime
35) Battle Realms + Winter of the Wolf
36) Die by the Sword + Expansion
37) The Journeyman Project 3
38) Worms 2
39) The Settlers 4
40) Robin Hood: The Legend of Sherwood
41) Conquest: Frontier Wars
42) Bloodrayne 2
43) Atlantis: The Lost Tales
44) Atlantis 3: The New World
45) F/A -18E Super Hornet
46) Combat Mission: Beyond Overlord
47) Interstate 82
48) Rune Classic
49) Chaos Overlords
50) Powerslide
51) Post Mortem
52) Speed Busters: American Highways
53) Megabyte Punch
54) The Banner Saga
55) Kentucky Route Zero
56) Soulbringer - EDIT on 3/11/2014: Reportedly has bad frame rates on Windows 8 (credit to VanishedOne)
57) Slave Zero

Games that are NOT "officially" on Windows 7 (but do run on XP, Vista, 8) on their game cards:

1) The Longest Journey - EDIT on 3/11/2014: Reportedly works well under Windows 7 (credit to Maighstir)
2) Real Myst
3) MDK 2
4) Blood 2: The Chosen
5) Independence War 2
6) Red Baron Pack
7) UFO: Aftermath
8) Disciples: Sacred Lands Gold
9) The Manhole
10) EVOLVA
11) Sensible Soccer 2006

Games that supposedly WORK "officially" on XP or Vista, according to their game cards:

1) The Incredible Machine Pack
2) Tex Murphy: Overseer
3) Gothic
4) The Interstate ’76 Arsenal
5) Messiah - EDIT on 3/11/2014: Reportedly works well under Windows 7 through nGlide (credit to Fever_Discordia)
6) Gorky 17
7) Silent Hunter II

Games NOT ON XP on their game cards:

1) Strike Suit Zero
2) Dracula Trilogy
3) Dust: An Elysian Tale
4) Giana Sisters: Rise of the Owlverlord
5) Pixeljunk Shooter
6) Ether One
7) Sudeki
8) Consortium: The Master Edition

Games NOT listed for BOTH XP or Vista on their game cards:

1) Windforge
2) FRACT OSC
3.) Sir, You Are Being Hunted

EDIT:

A user has helped out and linked some sites that is basically this list, but a bit more enhanced. Feel free to check them out:

http://www.gog.com/forum/general/windows_compatability_games_that_do_not_officially_run_on_specific_versions_of_windows/post33

There is no relation between later OS versions being absent from the GOG store page and whether the game will actually work on those later versions (it usually will). Some games have had the installers updated without changing the store page (e.g. Gothic includes a Windows 8-specific fix).

Most digital distributors only list whatever versions existed when the game was first added to that service so what GOG is doing for ongoing compatibility is far beyond what you get elsewhere.

I commend GOG for doing what they do, but this is by no means a stab at them, if that's what your referring to by your last statement. But in saying that, it would be nice if game pages could be updated, as potential customers might automatically think a game does not work even if it does. That's why I stated at the top of this list for any potential customer to research a title by means of it's game specific forum or GOG itself to see if there are any existing workarounds, and if they want to go through that hassle (or if there's no hassle at all and the game card just wasn't updated). It would be in the best interest of future customers to update the game pages, especially if it's someone who's very unfamiliar with older games.

Well, I found it useful, at least :)

Yeah, official support really means nothing.

I can agree with that, because there's a lot of folks out there that are really not knowledgeable at all when it comes to PCs and hardware/software. That's just the way it is.

King of Dragonpass is supposed to run on Win 8, but it doesn't for me.

Meanwhile, Gorky 17 isn't supposed to work on Win 8, but running the game in software render mode and turning off both anti-aliasing and anisotropic filtering makes it work.

Strangely enough, the following games are listed as Windows 8 compatible, but not Windows 7:
Disciples: Sacred Lands
Evolva
Real Myst

I was able to run the third game of the Dracula Trilogy in XP with no problems. I didn't try the first two, but the versions I had from GamersGate ran just fine, so I'd be surprised if the GOG ones didn't.

I believe the other four games on the "Not on XP" list require DirectX 10 or newer, and as such will never work with XP because DirectX 10 was not released for XP.

I've also wondered whether there's already a list like yours somewhere and didn't find it yet, and I think it would be very useful to have it! +1 Yes, it does: It means that GOG will give you your money back in case the game doesn't work on your OS. Sure, even games that don't officially support your OS might work on it, but if they don't, you're on your own, because you have been warned that they might not work.

I can run most windows 8 incompatible games just fine on my windows 8 (Gothic, Septerra core, Shogo, Alan Wake etc.).
Sometimes even the language matters for some reason - I can't run the English version of Still life, but the German version works like a charm.

Only on Nvidia card. ;)

Meh, at least it will maybe prod GOG to update the game cards so the compatibility information can be made more accurate, some of those marked as not compatible with Win8 are DOSBox games, I'd be surprised if they were really affected that much by OS version and Messiah is a LOT happier under Win7 since the recent update that sets it to run with nGLIDE!

I think gog.com needs to update the Operating System (OS) and list Windows 8.1 as well not just windows 8.

gog.com please make the video game developers who don't have support for Windows XP, Windows Vista, Windows 7, Windows 8, and Windows 8.1 to have support for all of those Windows versions.

Tower of Guns does not have Window XP support yet looking at the gog.com store page and the Steam store page it says it supports DirectX 9.0c.

Windforge does not have Windows XP and Windows 7 support.

I will also say this The Witcher 3: Wild Hunt will not have Windows XP support because it is DirectX 11 only and DirectX 11 is not supported on Windows XP. So I hope gog.com and CD Projekt RED add Windows XP and DirectX 9.0c support sometime after The Witcher 3: Wild Hunt is released for sale in a patch for free.

There are like 6 or 7 PC versions of video games that I seen on Steam that support DirectX 9, DirectX 10, and DirectX 11 and also support Windows XP, Windows Vista, Windows , Windows 8, and Windows 8.1.

I will be purchasing all of the video games from gog.com that support all 5 of those Windows versions if 1 of those 5 Windows versions are not supported I will not purchase those video games.