One of the games (the demanding one that is not available digitally) actually does work on Windows 10. Found this out by total accident.
Most free VM software that I'm aware of allows only a very small amount of VRAM (video memory) to be allocated to the virtual machine. I can check the hardware requirements of these games, and just hope they don't require more.
Microsoft should really do something about this problem, or at least restore the option to temporarily disable driver signing enforcement, which was the original workaround.