Without any problems or workarounds?

Probably not.
GOG update recently installators - added ddraw wrapper with cfg config executable. That needed exactly on Win8 and Win10 too(i ques).

Win8 and i think Win10 have speed problem (not just fps), but you can recognize it only if know how it must work (on Win7). Dont forget to enable directdraw\direct3d support in configurators.

You can use Disciples GLwrapper by verok(ser) - it have hack for speed up the game. 1.2 or 1.5 multiplier - and no matter how fast game work(ai think and any else) for you.

Personally I didn't have any problems whatsoever with GOG versions. I did not test the CD versions.

Thanks.

Until very recently yes, but I tried to get them to work today, and after trying everything I could possibly try, I give up. I can't even launch them.

Same here sadly. Is there a workaround I wonder?

That's unfortunate. As I said, it works for me -you may try changing some settings in the config, like using DirectDraw for Disciples 1 and Direct3D for Disciples 2 (I have those turned on).

Worked fine for me until yesterday. Now won't even launch.

Not sure if GoG have changed something or it was the Windows update but frustrating either way.

Yeah, same problem.

Very frustrating.

Has anyone contacted GOG about this yet?

Dont forget to check game files in Galaxy after install\update.
Better use GOG Downloader version.

Dont forget to intall updates, DirectX web installer - and then enable legacy directplay in Windows turn on\off features and components.

If the games used to work but suddenly stopped, then it most likely was caused by some update. You guys should post more details to determine what your systems have in common.
For the record - these games still work for me and my Windows 10 is up to date. I'm not using Galaxy but offline installers and I use McAfee on this system (antivirus software would be my first suspect in this case).

How do I determine if DIrectX 9c is installed on my computer? Because I think it is. I know DirectX 12 is installed, but how do I found out if older versions are installed too?

Does this screen shot show I already have DirectX 9c?

OK, this is so strange. The Steam version works perfectly for me. GOG's doesn't even want to load though. I wonder why? lol, weird :(