MM9 is completely broken and unplayabe on Win 10. I've followed what others have said to do on the forums but the black screen problem still presists making this game unplayable.

GOG should not host games that are broken without at least a disclaimer or banner stating that is may not work for certain OS's without tweaks. (Or provide a patched version, even if the patches are player/fan made.)

GOG should add a disclaimer and refund anyone that bought the version that cannot play it.

EDIT: For those that went far right, notice I didn't say to completely stop hosting, I said to add a disclaimer that they do not work for certain OS's (or state that patches are needed to work with possibly a link to the patch). For those that provided useful information, I appreciate it. The information you pointed to did fix the issues and I appreciate your taking the time to educate those of us that aren't as savvy.

https://www.gog.com/game/might_and_magic_9 doesn't say the game works on Win 10. "Works on: Windows (XP, Vista, 7)". Thus those with Win 10 are not eligible for refunds.

So, January next year when W7 is dropped does Gog make it work for W10 or keep selling it?

But they do. The MM9 gamecard says:

https://www.gog.com/game/might_and_magic_9

Works on: Windows (XP, Vista, 7)

See? No Windows 10 mentioned. As long as they state where it works (=is supported), then I don't see the problem.

Having said that, GOG might stop selling such games that don't work on Windows 10, as they know it will limit the number of buyers severely. Maybe GOG could also add filters to which OSes a game is supported.

For what it's worth, I just tried Might&Magic 9 on my Windows 10 laptop, and it works.

The vanilla GOG version installation seemed to otherwise work ok, but when diving into water, I did get the "black screen" problem, ie. everything is pitch black if you go underwater (from the starting point of the game, I ran outside and followed the path to the sea where there is a ship, and dived into the water).

I went to M&M subforum and found this message:

https://www.gog.com/forum/might_and_magic_series/might_magic_ix_fixes_all_in_one_place/post4

So download dgVoodoo2, uncompress it and copy these three files into your M&M9 installation folder:

D3D8.dll
D3DImm.dll
DDraw.dll

(they are under dgVoodoo2_6\MS\x86\)

Then the "can't see shit underwater" problem went away. As far as I can tell, the game now works quite fine for me under Windows 10. The only remaining issue is that the screen was stretched to fill the whole screen after applying dgVoodoo2, but I guess I can fix that somewhere either in Nvidia or dgVoodoo2 settings so that I get 4:3 aspect ratio (black borders on the sides of the screen). Of course the game is fully playable stretched too.

As for why GOG doesn't include these fixes automatically to their game, there may be lots of reasons. The fix might work for some while break the game for others, dgVoodoo2 authors want money for including their stuff in commercial releases, etc.

Anyway, for me the important thing is that it seems to be rather easy to get the GOG version to run ok on Windows 10.

Most issues you could ever have with older games can usually be fixed by the already mentioned dgVoodoo. There are also DxWnd and nGlide.

When something doesn't work or works badly (terrible framerate or some other issues), I usually try them in that order and in most cases, one of them gets the game working smoothly. These methods are also great as you can easily force some older games into borderless window if you want to, change their aspect ratio, pick your own resolution and tons of other stuff.

dgVoodoo is pretty easy to use.

DxWnd requires some knowledge as the number of options it has is simply overwhelming so finding the relevant ones can be difficult sometimes.

And nGlide is a good last resort.

A third last resort is to throw it to Wine.

And if they keep selling games after W7 is dumped for W10 that don't work then they will incur the same problem again and that ain't good customer relations.

They still have Interstate 76 and probably a few other games that are only supported on Win XP and Vista.

Okay.

GOG has gradually been making several older games compatible with W10 and other OS. I remember that they managed to make "The Longest Journey" playable on W7, when it was only playble on WinXP.
It's likely that they'll make M&MX compatible somewhere down the road.

I've recently played Interstate 76 on W7(64b) and it works perfectly. I suppose it's a possibility (since its' one of the oldest games being sold here) that GOG never bothered to change the specs info :P

I remember reading at some point that GOG contributed to dgVoodoo, I wonder why don't they patch all games that need it with it.

I haven't tried it recently, but one issue with it was that the physics engine somehow relied on CPU speed. It meant that driving didn't work as it should have (e.g. I recall there was some mission or something where you needed to jump over a chasm with the car; or was it merely racing against your buddy? And it couldn't be done with modern CPUs), and then the flamethrower weapon didn't work correctly, it would hit only like half a meter from the car.

Did you finish the game successfully? I think I might try the game again, I recall I had lots of problems years ago to get it work even on an old IBM ThinkPad T40 laptop, having to use some utility to slow down the CPU etc.

Hmmm, that reminds me, in modern laptops and Windows it is actually quite easy to slow down the CPU, through the use of Power Plans. I wonder if that works with I76?

I admit that I haven't finished the game (I only finished the game back when it was released) but I installed it a couple of years ago to see if it played fine.
I even installed it again some hours ago. As far as I can see the speed is the same as when I played it in the 90s. Didn't try the flamethrower, though.