I managed to open the iso by briefly installing my copy of PowerISO on another virtual machine, extracting the contents of the iso there, copying them to the Mac, and then reverting that virtual machine to its backup, before remaking the iso using
https://matt.berther.io/2008/12/14/crea ... er-in-osx/. That worked.
However, while my Windows 98 SE virtual machine can support 2D resolutions at 32-bit colour depth all the way up to 1,920 x 1,440 (and this was in use when I took the screenshot at the top of this topic), and it also has DirectX 9 installed (the latest DiretX that operating system will support and much better than the DirectX 2 supplied with the game), when I open Marathon 2 on it, only 256 colours are available (8-bit colour depth) and the other option, "Thousands", (16-bit colour depth) is greyed out, even though even "High Resolution" is a lot less than 1,920 x 1,440 (as shown by the fact that the window shrinks considerably when I launch the game). Is there anything I can do to get "Thousands" available? I am using VMWare Fusion to run these virtual machines, and the hardware version of that virtual machine is version 9, which to the best of my knowledge is the highest that works with Windows 98 SE. This does mean that I can't simply make more of the RAM available for graphics, which I can by changing the virtual machine settings for a virtual machine which uses a later hardware version.