Actually this solved the problem on two of my systems running Windows 7 64 bit, a friend also said that it worked for him. No idea why it didn't do the trick for you.

As mentioned in other threads the reason that works on Windows 10 is because the OS has a compatibility database that has an entry for that game which is broken, so renaming it bypasses the compatibility entry. Windows 7 also has such a database, and I have it open in Microsoft Application Compatibility Toolkit right now and there is no entry for that game present. GOG also supplies databases with some of their games for Microsoft ACT (Dracula, Dracula 2 being a couple examples), but Commandos does not appear to have an entry.

So on my system, I do not see any evidence the binary is being handled specially by Windows, and I can confirm that renaming it to abcdefghijklmnop.exe did not stop the DX5 error from popping up. If it worked for you and you're using the same OS then there is obviously something different between our two systems for sure. :/

Ah crap, I just remembered, two of the systems I mentioned were actually running Windows 8 and on the third one, which actually did run Windows 7 x64, I did not even have to use that fix. Sorry.

Shit happens. :)

I'll hammer the web sometime and see if I can find something but I'm doubting it ATM. Other options include trying a network-isolated cloned XP VM, and trying to install it in Linux and using Wine. I do have an old PC I could throw XP on non-networked also but that would be a last ditch. :)

I was trying to install it to test something for someone else so not a huge deal ATM, but the sad thing is that an increasing number of games have breakage like this immediately after install I'm finding. I'm keeping track of them in a spreadsheet with wiki pages for each game for my findings/workarounds etc. though, but man... lots more games are broken than I would expect. GOG support has workarounds for a number of them though which is pretty nice, but other games they are increasingly throwing out lengthy form letters that tell you to do boilerplate things, many of which you told them in your initial report you already did. It's like they are just recently starting to respond to some support requests with an auto-send-formletter response without even reading the request. I hope that was just a couple of flukes though as they normally are pretty good with stuff.

I should go through my library alphabetically one of these days and test install every game and do a little QA test run of sorts on them all and take notes though, or perhaps even try to rally up a number of other interested parties here in the community to work together to do the same thing. Seems like there are solutions for a lot of common problems out there but not all pulled together in one spot, and often simple fixes that GOG could include directly in a game's installer/configuration they just leave broken and maybe put an entry in a support article for it. Still 1000 times better than Steam mind you, but room for improvement too. :)

To fix this on windows 10 rename comandos.exe in the installation folder (for me on GOGclient this is: C:\Program Files (x86)\GalaxyClient\Games\Commandos\) to commandos.exe

Windows 10 seems to have some sort of compatibility support built in by .exe ref ....

Remember to repoint any shortcuts!

- I installed COMMANDOS: Behind Enemy Lines few mins ago. I only renamed the file "commandos" to "commandos.exe" and that worked. Did nothing else. On Windows 10 PC.

Worked for me as well on Windows 10.

Ok it works by renaming Comandos.exe to Commandos.exe, but where are the videos? There's no intro video or any other cutscene. How can I fix that?

I did the same...can't believe it was that simple...
I also only renamed the file "commandos" to "commandos.exe" and that worked. On Windows 10 PC.

- I don't know. Worked just fine for me after I renamed the file. Introes, everything.

Which Windows do you have? I have Windows 10 64bit.

1.
rename comandos.exe to commandos.exe.
2.
open cmd.exe as admin
3.
go to path where commandos is installt.
4.
enter mklink comandos.exe commandos.exe
5.
Play in GoGGalaxy

This works perfectly

Thanks, that was perfect.

Somebody should pin this thread. Thanks for the solution btw.