Strange - My base game is on a CD as well and works fine (as much as this can be said for the base game of HoI3) on Windows10.
Look, though: I bought the game and all the expansions (full price mind you). I am not going to buy it again, just because GG is breaking the contract. What do you mean, they are not able to do anything about the issue? The very least thing they could do, is to admit they screwed up, apologize and give me (and all other purchasers) a voucher for their shop (EDIT: Or preferably one for another shop that actually still sells the title - for the amount the entire complete package costs there, as the expansions are not guranteed to work cross-vendors).
This attitude, that it´s okay to yank back what you bought by the one´s you bought it from is entirely inacceptable. If it´s due to Windows breaking compatibility, i am willing to give it a pass, but this is not the case here. The setup file is simply broken (and used to work just fine on Win10) and to top it all off, it´s been a reported issue for almost a year and no one in charge seems to think it´s worth fixing, cause "you can re-buy it somewhere else for cheap". If anything GG can buy it for me somewhere else for cheap.
Instead, what i got from GG is a standard reply (in english, though my complaint was filed in german, cause the form was in german), stating that the tech team can not reproduce the error (implying it´s my fault - i did sent a link to this thread to make sure they wouldnt give me the "have you tried turning it off and back on again"-treatment - to no avail, as it seems). I replied, asking if they download it from the same server as i would - and if they were not, if copying the file from that server to the other might not solve the issue. I probably gave everyone in their office a good laugh, for my naivité of taking their reply seriously. They probably have a button that generates this reply automatically and noone even really looked into it at all. Cause people these days are just willing to take it, apparently.
PS: I wonder if they are still offering the title on their store page.
PPS: No they dont, and aplogies: Kovax said so.
PPPS: Not to brag here, but remember those little colored edges on the counters that indicate "out of supply" and "command delay"? That was my idea. I posted it, some dev jumped in and said that it was a good idea and it got incorporated into the game next patch / expansion (i dont remember which). And now, i cannot even play the game anymore. At least the issue brought me back here - good to see some old names again.