Commander X16

For what it's worth the game I'm porting to the CX16, Another World, is a 16-bit game. And yes it is quite difficult, as the original also used 32-bit data types. There is also a port of the Sierra AGI Game engine, which was also 16-bit.

SO it's not completely unrealistic to consider it might be possible... Obviously the 32-bit DOS is probably out of the question, but an earlier version of DOS could potentially be emulated.

It definitely wouldn't be easy. DOS has a more complicated memory structure and addressing method, which allows for up to 1mb of memory (the CX16 only has 512kb base version), so that would be very tricky to navigate (it's not "banked" like the CX16, it's segmented). Not to mention it would be very slow. Probably 10 times slower. All the instructions are 16-bit. Sound and IO would be very tricky too.

It would need someone who is an expert in 65c02 assembly, and 8086 assembly, and a deep understanding of both architectures.

Basically, yes it can be done, but without any incentive there's literally no reason to undertake such a massive project.

I've wrestled with how to explain the X16 ...

I had to explain it to my wife this weekend. She didn't understand my excitement of something that is so far from the capabilities of a modern computer. The best analogy I could come up with, was a car buff could certainly drive a modern car with all the luxuries and conveniences possible, but to find yourself in a 67 Shelby Mustang isn't even comparable. It's like back when you had to drive the car for real, shifting gears, you could feel the hardware and you needed to understand how it worked. The same thing with 8bit computers. You have to know the hardware and how to squeeze every extra byte and clock cycle you can.