Did all devs say such things? I never see soft dev who admit something wrong on his end. And a lot devs like this one. So they prefectly udnerstand how to set up their OS. Especially Win8+. They perfectly know that 1280x1024 is 4:3(*) and thye have fully understand options in dxcfg(*), how to properly install games and gaming clients...

... * or they not. Lamo's everywhere!

There is no fix needed. Any digital versions of the game, US Gold 4 CD +DLC +patches (and some of else retail editions with patches) - on ANY OS run perfectly fine.
There is issues during gameplay on OS starting Win8+. WinVista+ require UseD3D=1 in game settings (WinXP also better to set it on, for less AI move time).

GOG 2019 update bring back something of missed content from Cds (still patches missed, DLC missed, some of CD contet still been missed)(GOG Galaxy miss that 12 blank heroes restored in 2019 - this time offline installer superior).
And GOG 2019 update bring Discipels 2 build of GOG DX Wrapper - which one solve Win8\10+ issues. Game now work perfectly fine on Win10.

Discipels(2)GL wrapper mod - is modification. it require game to be running and set-up. It require configeditor settings first. Only resolution is 800x600 for it (and rename _ddraw.dll for use GL mod).
it is improve some QoL, but it is not for compatibility issues. Its not a main goal, although it same as DXCFG can fix same issues on Win8+ (same slowness without FPS drop and long AI turns even with UseD3D).

Use 3rd party sites to download Verok's works or his Patreon.

If you think your Win10 is perfectly setup - think again. Something prevent game to work on your OS. Some of the first posts here already confirmed GOG update did improve game compatibility and working on Win10. This is simple fact - game not work on your OS. How it can be named properly set? Turn off Win DEP, Defender, reinstall game's, reinstall to proper path's, verify installation in Galaxy, properly set up game and DXCFG. Especially resolution and refreshrate(!). Windowed require 800x600 and stretch-to-full(!) options as well as refreshrate identical to desktop(!). Fullscreen require x768 (again, recheck wat refreshrates supported for every resolutions of your display), because 1024p is not a 4:3 and only will work on 5:4 'office' displays.

Even for 5:4 display it better set x768 game 4:3 original aspect resolution. And play with black bars.
Same for any widescreen displays. Set x768 (if your display is above x768), make sure video driver, diplay settings (OSD, especially for TV), game GOG DXCFG wrappers - all set to Keep Aspect ratio. Play with black bars.

And only then optionally further improve game with DisciplesGL mod, getting zoomed out widescreen support. My opinion, better avoid using widescreen hack battles hack - it still be borderless-fullscreen-windowed and still widescreen - but more proper UI in battle mod. Widescreen hack change background (more variations and wider images), but wrongly change UI, although all issues are fixed for latest mod build.
DisciplesGL mod require same build and settings to be compatible in multiplayer. Again, to use it - set 800x600, stretch-to-full and rename _ddraw.dll.

Hello everyone, I am posting what I did to make the game run on Windows 11 without using any .exe files from somewhere:

1. Remove ddraw.dll, run Disciples 2, let W11 install DirectPlay
2. Resolution set to 1280x1024, check UseDirect 3D, Strech to full-screen, Compatibility mode
3. Check compatibility mode for Windows XP Service Pack 2, 16-bit graphics, disable fullscreen opitimization, run as administrator

I have around 10 hours of in-game time with no crashes or stuttering. Hope this helps someone, someday!

Sry, but all wrong.
1. renaming GOGs ddraw revert required on mobile Windows (8+) fixes. Without that game will not wrok properly, although it start fine an there is no FPS drop during gameplay (if you also enable UseD3D which ones required on WinVista\7 and on Win8+) (most noticeable issue - increased AI turns issue, probably micro-freezes not affect FPS not so noticeable if you didnt play on normal Windows). Install DirectPlay manually and restart OS by Alt+F4-Restart - this is how Win8+ should be restarted (also depend on settings better on Win7), not Shutdown.

Even WinVista\7 didnt respect older DirectX Ddraw and D3D. Mobile's Windows 8+ broke even more recent D3D9 games.

2. In-game resolution is 1024x768 (if you display higher than 1366x768). 1280x1024 is wrong proportions added in patches to support office 5:4 displays where it still better set 4:3 aspect for the games as it indent to. Stretch-to-full is optional for fullscreen (it add background, ofc you turn it off - you set wrong resolution so background looks for your widescreen displays too large, also you ost likely didnt set Keep Aspect ration in video driver (not by default)).
Ingame compatibility mode not needed and work worse.
For windowed mode set 800x00 and stretch-to-fullscreen. Same required for using Disciples(1\2)GL.

3. There is no need for compatibility modes on exe except optionally pre-set by GOG 'highdpiaware' (fullscreen optimisation disabled).
For games require WinXP compatibility - chose Sp3.

As for admin mode. It required for GOG's dxcfg.exe (dont forget to configure it, still Keep Aspect ratio set there) and for ConfigEdit.exe from game. Game and Editor itself should work, not require admin even for first start (offline version). It not require admin rights, system folders and windows registry. Work without VirtualStore if installed to \Games\.
Ofc you should install games and clients (GOG-Galaxy\Steam) to D(x):\Games\Game-name-2\.

if your game didnt start without renaming ddraw.dll - there is something wrong on your system. Again, start from re-installing game to X:\Games\. Thta solve few security issues with OS (admin right not solve everything) and more with 3rd party security apps\services (they ignore run as admin command for apps in Program Files).
Check what process interfere game exe by Task Manager - Process\Details (not main tab window of course!) - game exe - Analyse Wait Chain. Close all apps.

I think ddraw.dll in Disciples 2 folder is just corrupted. I copied it from C:\Windows\System32 and paste to game folder whit replacing the old one. And the game run well (on windows 11)

This worked for me, unlike the rest of the fixes. Thanks.

Thank you, lol. NOTHING was working until i tried this. 4/5/2023

Well... silly me just downloaded some wrapper, enhancing the game quite nicely .....

like everyone with a hommnoinnmon background would know..... right chaps ;P

https://heroes3wog.net/disciples-12-hd-mod-gl-wrapper/

Replaced ddraw.dll from the game folder with the one from C:\Windows\System32.
Executable properties set to Compatibility XP Sp2, 16 bit color, disable fullscreen optimizations, run as admin. Dxcfg set to 1280x768,full screen. Configuration editor set as 1280x768, checked Direct3D, stretch to full screen, compat mode. Allow Windows 10 install DirectPlay. Working well now. Thank you everyone!

Can anyone help me? My game crashes in a certain round end of turn after the last opponent moved and the game does the auto-save. Already tried to remove the savegame folder to overcome the bug and tried different modes (im running the wrapper patch) but nothing seems to heal the crashes :/

This worked for men, thank you!