Another thing to try, if this means 16 core processor,

"System Info:
WinNT 6.2 #Processor: 16 "

is to use imagecfg.exe to limit the number of cores that the game .exe has access to. I would suggest 1 to 4.

Runs on an older update file (7 years ago). When you are in the "gog" application, you can select the update file to be installed in the game settings. The new one (3 years old) is out of order and the old one (7 years old) is working.

No. It is GOG's wrapper that fix Win8\Win10 compatibility. Newer version should work better. Just start dxcfg.exe and configure it. Or rename _ddraw.dll - but you get latency\slowness (without FPS drop) on Win8\Win10 in fullscreen mode.

Something prevent wrapper to work. It is better to use newer version as well as GOG's wrapper.

Rename ddraw.dll if you want to use Verk's wrapper (this is optional move, borh wrapper technically can work together).
Remove compatibilities excemt admin run. There is at least one pre-set from GOG to game exe at installation (both offline and Galaxy build). Better remove it. Especially if you use Verok or any else wrappers (including GOG's one, GOG mess up set-in that compatibilities to every games when it needed and not)

Edit: Works now, thanks to the "Disciples I & II GL Wrapper" posted by Liso1 on August 2, 2022 at the heroes3wog net page.

It's nested in the as
Heroes 3.5: In the Wake of Gods Portal > Disciples HD mod (GL Wrapper)

The link looks like this
"
heroes3wog
.
net/
disciples-12-hd-mod-gl-wrapper/
"

*****
Just bough Disciples 2 Gold on GOG.

After installing I press play on the GOG Galaxy launcher and the screen turn black then nothing happens.

Please help.

AppCompatibilityChecker by Verok
http://disk.yandex.com/d/37-Y0GVgWUATJA

it cannot remove compatiblities installed by sdb-packages (ms ACT\ADK app)(installed with the game by DISMM service - cmd window appear duting installation of the game).
But this tool can show it. Use WinRegistry and manually clear Windwos system some sub-folder. Or dowanlod ADK (ACT 5.6 for Win8 or eallier) to remvoe it.

look to .sdb files.

There is sdb file in ingame folder. You can open it by WordPad or HxD and look where it stored.

Added Make Disciples 2 work in modern OS to wishlist.

https://www.gog.com/wishlist/games/make_disciples_2_work_on_modern_os

I'm probably just talking to the wind but there is always hope.

What is a modern OS? Linux? Not modern too...
If you mean broken Windows 10 - GOG already implement Win10 fix in 2019. Microsoft broke it again.
As well as users themselfs. Properly setup game settings.

I tried some of the steps you've recommended and it worked!!! Thank you so much. I must say, Disciples II is literally the first game on GOG that had me troubleshooting for an hour, before I ran into this thread. Majority of older classics bought here worked perfectly on new machines, even Disciples: Gold worked, despite crashing every now and then.

For Dis2 game work perfectly fine, because of ddraw.dll from GOG file.
For Dis2 ROTE GOG made GOG-Galaxy update and broke it, they forget put back that GOG's DX wrapper there. Also remove older build from Galaxy (even from API as private branch, there is no rollback feature for ROTE available, nice job GOG), and forget to update offline installer (likely for us).

Anything of what been say here not needed. Except of course installing gaming clients like Steam\Galaxy and games itself to D(*x*):\Games\*Game-name-2*\ and run Config anyway as admin.
Same for DXCFG.exe if it still there for your version.

It just usual random things. 'I try everything something help i dont know what exactly i spread that to everyone'. Do not wrote it if it is literally 'i dont know'. You should know what you do did and what suggest.
Stretching to widescreen is default video driver settings. That not matter which one resolution you set in the game. 800x600 is equal to 1024x768 - i mean they both 4:3. 1280x1024 is wrong 5:4 no more supported properly by nowadays cards and 16:9 displays.
You must set Keep Aspect ratio in video driver. To play widescreen use DisciplesGL wrapper mod.

So I got this to work after much fenagling.

* Renamed DDraw.dll to DDraw.dll.bak
* Changed the game resolution to 800x600 on both config programs. This made the game succesfully open on my old 4:3 monitor.
* Changed the screen mode of the game to windowed on dxcfg.exe, this lets me move the game to main 16:9 monitor and raise the resolution up to 1280x1024.
* Changed the resolution to 1920x1080 and now it finally runs in widescreen and seemingly in borderless fullscreen, though stretched.
* Set the Aspect Ratio Correction setting to Enabled.

In the attachment is my final settings. Hope this works for you.

this lets me move the game to main 16:9 monitor and raise the resolution up to 1280x1024

this one uncler. Moving to another monitor\desktop... but how 1280x1024? Ad this is not 4:3. Game do not support 120x960, so 1024x768 is maximum.

If check Aspect correction in dxcfg resolution option "ignored". Not exactlty... Still applied. To completely ignore it Scaling fir -> Integer.

Still nothing of this is neccesary. Multiple displays can be issue, but that should be fixed by system settings.
As for ConfigEdit.exe and dxcfg.exe - they not require anything special... except UseD3D=1

DXCFG can be compeltyely set to 'by app_(default)'. For fullscreen and for windowed. It still do main job solving issue with broken DirectX in Win8+. Windowed require set in CofigEdit and 800x600 and strecth-to-fullscreen option (yes, it needed for windowed).

Refreshrate better set manually in ini file. And ofc double check whoich ones refreshrate are supported on all of your displays on all resolutions. 1024x768 too. Usually better set 60hz. But for windowed you will be equal to what in fact set on Desktop.
Differences in refreshrate on displays can bring issues in general and games.

Renaming ddraw turn off dxcfg. And turn off fixing broken Win8+ DirectX. You will get slowness and longer AI turns. Not in windowed mode, only in fullscreen.

DXCFG removed from current GOG Galaxy build doe to mistake of this update.

game didnt start. After GL Wrapper its good :)

I renamed ddraw.dll, then an error's screen appears, so I have modified the shortcut's properties to be exe on XP SP 2 and it worked.

This fixed the problem for me. I had to set windowed mode with dxcfg.exe, after that it worked.