OneMagpie: I managed to get my virtual machine running last night and it plays it like a dream. There's some very small micro-stuttering but it's honestly not that big of a deal, so I'll outline the steps here in case anyone wants to give it a go and they didn't know how to get one running.
This isn't really a fix, this is the biggest workaround ever, but it works.
GOG won't let me post links yet so you'll need to copypaste them into your browser. Sorry!
1: Get VMWare player here:
vmware.com/products/workstation-player/workstation-player-evaluation.html
2: Get a Windows XP bootable iso file. I got one at the link below, but if you don't trust it I think there's one on internetarchive.org, and a few other websites too.
softsfreak.com/download-windows-xp-sp3-bootable-iso.html
3: Make a new virtual machine in VMware Player. Set it to Windows XP Professional and select the iso as the boot disk.
You should leave the specs alone (CPUs, RAM, etc.) until later as I've found messing with them here can break it sometimes.
4: Start the VM and install windows.
5: Once you have your shiny new (or old) Windows XP machine running, go to the top left of the window, and go to Player > Manage > Install VMWare Tools. After that, restart the VM. If you want to change the specs of your VM, now's a good time, just turn it off, edit them, and turn it back on.
6: Go to GOG on your normal pc, go to Wizardry 8, Downloads/Extras or whatever it's called, and download the backup setup.exe. Once that's finished it'll be in the !Downloads folder in you Wizardry 8 directory. Drag that onto the desktop of your VM and it'll copy it over.
7: Install the game, and play.
Wow, thanks for posting this. I'm going to try and see if I can somehow rig Wizardry 8 into running some other way, but I'll be sure to keep this in mind if all else fails.