Christliar: Like the title says. It comes up with a NEBULA ASSERTION: Unable to save texture! error. You can check the attached screenshot for details. After some googling, it appears to be a DirectX problem, more specifically the game was designed for DX9 and doesn't play well with newer versions. I'd have thought GOG have tested that before advertising the game running on Win 7, 8, and 10. It technically runs, of course, you just can't save. I've used all the possible graphics options to no avail. The game is installed on an SSD, and I tried running it as administrator.
To start, check out:
https://support.gog.com/hc/en-us/articles/213039345?product=gog This section might be pertinent.
3) Install the June 2010 DirectX runtime package, then use the DirectX web installer, as your current DirectX may have become corrupt over time.
You can find the ZIP file containing the 2010 package installation files here:
https://www.microsoft.com/download/details.aspx?id=8109 You will have to extract the files into some folder, then open that folder and launch the DXSETUP.exe file in order to proceed with the installation.
Afterwards, download the latest DirectX web installer use it as well:
http://www.microsoft.com/download/details.aspx?id=35 4) If the above don't help, right-click the game's shortcut, go to Properties -> Compatibility and try different compatibility modes before attempting to launch the game again.
Beyond that, I'm not sure. I'm running it on the latest version of Windows 10, with run as admin and disable fullscreen optimizations checked on the executable's properties.