I have configured my system under video settings, but I can't see that the game is running in higher resolution (still looks like 640x480...

Is it just an upscale? or am I missing something??

Yes it simply upscales

Even with upscaling I can see no difference between the two modes. They look visually the same to me so I'm failing to see the point.

They should look the same, that's what the upscaling is doing. The point is that the classic version will run in the original resolution, which some modern monitors and Windows may have issues displaying (or will display very small), whilst the GOG version will use your native resolution and so not have these issues. It isn't a HD mod, though, so it will not look any different.

I understand. But I can't be the only one who assumed high res ment support for modern resolutions including Widscreen. Perhaps it would be good for GoG to clarifiy in the description. I understand their goal is most likely to present the game on modern hardware so that it most closely mimics the way things were back in the day and that makes total sense in hindsite, but that wasn't my original thought.

It does support widescreen, but you might be right that clarification might be needed; the original will simply set the resolution to 640x480 and on many monitors this is simply stretched to fill the full with of the display. The GOG dx version instead runs at a widescreen resolution and adds black bars to keep the game at the correct 4:3 resolution, it's better but it's the bare minimum level of support for widescreen.
(see attachment for example)

No worries, you're not alone. :)
I still think the description is a bit unclear, and I also wonder what bugs were fixed. 1.09 didn't have many to begin with, aside from the dupe thing.
At least they added the aspect ratio upscaling bit.

I respectfully disagree. Have you read the DSF bug list? The game has few critical (game-breaking, extremely frustrating, etc.) bugs, but it has quite a few that you will encounter in ordinary gameplay.

I've played my old, non-GOG Diablo for the past weeks now, and haven't run into anything frustrating or game breaking, other than the high level chain lightning bug.
But I do stand corrected, since that are a lot of bugs. Did GOG actually fix any of them though, since duping is still in there?

Thanks. So GOG is pretty much flat out lying in their description then. Not cool.

Well, not every graphics card and/or monitor properly scales "non-standard" (by current Windows specs) resolutions to fit the screen in the proper, original 4:3 full-screen mode.

Some people get "postage stamps" in the middle of a sea of black. Others get "streeeeeetttttcccched out" images, with the 4:3 original screen fully filling a 16:9 (or even larger widescreen format) screen.

The "scaling" mode INTERNALLY (ie, without relying on your graphics card or monitor to do the work) makes the original presentation of Diablo look right on ANY modern hardware.

If you have a graphics card and/or monitor which properly scales FOR you... you won't notice a different. THIS... yep.

Everyone with this question, please do take a look at Anders' attached image, which is very effective at explaining the issue.

Given the game's age and how many years Blizzard ignored it completely, I'd be a bit surprised if Blizzard even can create a new build for this. My guess is that at least one of the following is true:

- They've misplaced some or all of the source code. (Last real patch was 2001. How many times since then would they have retired out/upgraded key computers that would be involved?)
- They no longer have the build environment they used back then, and modern compilers may not accept the old code. (It's somewhat common for modern compilers to disallow things that were never valid code, but that old compilers happened to accept anyway. If you're lucky, the compiler disallows it by refusing your code. If you're unlucky, the compiler accepts it and produces the wrong result.)
- They no longer have the supporting pieces (Smacker, DirectX, etc.), and any modern replacements are not drop-in compatible, therefore requiring developers to modify the Diablo code just to get it to work with the replacement. They almost certainly don't have anybody left who knows the code well enough to quickly make such changes.