Sorry, Windows 8 and 10 dropped support for switching to 16 bit colour, with the only way to do so through the compatibility options for specific applications.
I'm going to claim I remembered that dropdown option from when I set up my Win 10 system, and that is why I assumed it could still switch to 16 bit colour. biggrin

In any case, I played the original release of the game with Win 98 and XP in 32 bit colour mode (and the updated version in Win 7), and never had an issue. I have not tried it on my Win 10 system yet.