Ahem.

You never list what your graphics card or OS are.
You don't reference who and where advised you to upgrade.
You don't describe clearly your problems before or after the upgrade.
You never follow up with people who try to help you out.
You were explicitly warned that Commandos DOES NOT work well on Windows 8.

Either give us some useful information to work with, or kindly FUCK OFF!

I had the same issue (on the steam version) after upgrading catalyst drivers on my HD 7950.
The fix was disabling soft shadows and frame buffer in graphic options.

First of all, in case You have forgotten, You represent the name of the GOG company, not Yourself. So whether You like it or not, You are forbidden to use F-words toward me. You want to get fired?
As for the Graphic card drivers, what does it matter - the point is the game should work no matter what drivers are installed. It should not crash after an update.
And how do You I do not follow others' advices - You have any proof of that?
And with Commandos 3 - This is just ridiculous. Don't tell me this was some kind of programming issue, like You were albe to make 'Behind Enemy Lines' ,'Beyond the Call of Duty' and 'Men of Courage' work fine on Windows 8, but not 'Destination Berlin' which is the youngest of them all.

And the most important part -I paid GOG for the games, so I have the right to demand them to fix the purchased goods when they malfunction for no apparent reason.

If You do not understand this, then Scar in Polish put it best:
https://www.youtube.com/watch?v=aWfpkUY-KTs

Wykletypl, Spinorial does not work for GOG.com. This forum is for discussions between users, if you need help directly from the GOG staff, you're supposed to open a ticked via this form: http://www.gog.com/support/contact

As for your problem, unfortunately it's not that uncommon that new drivers cause issues with old software, especially games. I've had my share of problems with Bioware games and Nvidia updates too. GOG tries to ensure compatibility for as many systems as possible, but that of course doesn't guarantee a 100% success rate.

Contact Support and explain the problem clearly. If they can't help you, ask for a refund. You may also keep asking in the forum if you wish, but then you're going to have to provide more details.

As was just explained to you, I don't in fact work for GOG. Every single snide remark I make here comes out of the boundless goodness of my liver. And if some of them actually end up being helpful to people, you're welcome. I'm quite flattered that you thought so highly of me, though; thank you!

Now, to try to be helpful one last time:

GOG didn't make Commandos, nor did they re-code the games to work. That all came from files made by Pyro or through hacks. Sadly, C3 never worked properly with Win8, but we have only Pyro to blame for that. How did they do it? Beats me. Actually, I have some theories somewhere in my relevant post, not least that Windows Vista, 7 or 8 didn't even exist back then, but in the end, I'm mostly clueless. One thing I know for a fact: GOG never claimed that C3 works with Win8. You bought it at your own risk. Still, with C2 working perfectly fine, the loss is minimal.

Any effort I make to get C3, KotOR, or anything else running, I do on my own time, for my own passion, with no pay or even much in the way of gratitude. I don't expect any; after all, it's still not working quite right. What I do expect, however, is when someone comes and asks me for help, and I reply to them with some suggestions, they come back to me with feedback - did it work or not or did they need something else. You asked for help, in the C3 thread, and I replied. And I never heard back whether it helped or not. So please forgive me if I'm not quite inclined to treat your rambling posts with much courtesy or patience.

Which brings us to this one. You play on a PC. Congratulations! It's a fabulous platform. Among its benefits, though not limited to it, is incredible customization. For video, that means you can play on an nVidia, or AMD, or older ATI, or Intel, or even an old S3 or Matrox or something. There are limitless possibilities and, unfortunately, it's very hard to account for all of them. So, when you come in here and ask - politely - for help from your fellow gamers, you need to offer details on what you need help with, aka your PC's specs. Without that, we can only take blind guesses. If you contact GOG support, you'll need to offer these same things - even they aren't omniscient to know the idiosyncrasies of your machine. GOG offer a money-back guarantee, but only if you are willing to help them troubleshoot your problem first. So, instead of bombastically proclaiming your consumer rights, make an effort to help those who try to help you. Everyone is better off that way.

Now, do you still want help?

It did help. Thank You for helping with this issue.

This list should be stickied on all forums here, there are so many people who can't be bothered to list any useful information, and go straight to bitching.

you know, as far as I know, some games on Gog, like Dungeon Keeper 2, do include a patch that enables them to work on Windows 8 and 8.1 . The way I see it, somebody had to write that patch, and since most of these producers are no longer on the market, it must have been someone on GOG. Besides, just because GOG does not say it, doesn't mean they cannot include that patch with later updates - and it might be actually necessary, given the fact that Windows 8 and 8.1 will be more and more popular on PCs.

Now, as for the help, I did in fact try the trick You showed, and for some reason, they still didn't work. So, of course I still would appreciate any kind of that.

On the side note, I am still amazed on how many times people overreact just because somebody, probably, had a bad day, and unintentionally ranted. Cause seriously, me bashing GOG over a stupid game... Don't You think I have more important things to do?

It wasn't the rant I was reacting to, but the total lack of usable information in your post. I too have more important things to do, yet here I am trying, however unsuccessfully, to help people out.

The DK2 patch may well have come from the community: it's fanbase is quite a bit larger, so it's not surprising that more fixes and unofficial support exist for it, as opposed to Commandos. Even if it was homebrewed by GOG, the analogy is faulty. The games are different, their code is different, the problem that prevented Win8 functionality is probably different. GOG may even have obtained the source code for DK2, whereas I'm absolutely sure they don't have the one for Commandos 3. And if they somehow, at some point, manage to get the game working on Win8, I'd be among the happiest. For now, I'm trying whatever, whenever.

As to the Win8 popularity, it's actually almost certain not to grow: Win10 is scheduled to come out in 2015 and most Win7 users are holding off on upgrading until then.

1. Microsoft made the flat statment dx12 is to be 8.1 and 10 ONLY... that will kill gaming on 7 and 8 imo.
2. Yes, Please sticky the list... I'm so sick of people saying my computer does not work but I don't want to post any details.