Trying to play MM7 again. Using a Windows 10 computer. It was a Windows 7 that I just upgraded for free. Still figure it's well enough to play an old game like MM7. Not seeing anything that helps with my problem though. Try to open the game either from GoG launcher or directly downloaded on my computer and I'm getting a DirectDrawErr.

Script goes as follows;

DDERR_UNSUPPORTED in file:
D:\mm7Src_eng\MM7\Code\GammaControl.cpp
at line number: 87

Any tips?

That is because with windows 10/11 this is considered a legacy component and starts off disabled. You will need to enable this feature.

DirectDraw Error Windows 11/10
In Windows 11/10, your game may not open with DirectDraw Error dderr_unsupported. This often happens when you try to play legacy games like Diablo, Age of Empires, or Diablo II. Usually, this error is accompanied by different error codes like 16385.

When analyzing this issue, you may find various possible reasons, for example, the game runs on full screen, the game is not compatible with Windows 11/10, there is a graphical rendering issue, DirectX is old/damaged/missing, and more.

Fortunately, DirectDraw Error can be fixed, and let’s go to see how to troubleshoot it.

Fixes for DirectDraw Error Windows 10/11 in Legacy Games
Enable DirectDraw and Direct3D
Firstly, you should make sure both DirectDraw and Direct3D are enabled to fix Windows 10/11 DirectDraw Error. Once either of them is disabled, you may run into a related error code.

Step 1: Type dxdiag to the search box and run the command to open DirectX Diagnostic Tool.

Step 2: Navigate to the Display tab and see if DirectDraw Acceleration and Direct3D Acceleration are enabled or not. If they are enabled, skip to the next method. If they are disabled, continue step 3.

Step 3: Press Win + R, type appwiz.cpl and click OK to open Programs and Features.

Step 4: Click the Turn Windows features on or off link.

Step 5: Scroll down to find the Legacy Components section and check the box of DirectPlay.

Step 6: Click OK to save the change.