Is the goal is to just make development faster and simpler, but still have everything run on the PC-Engine?
Why not just run everything on a microcontroller and use the console for video, audio, and input? That way you can just write everything in C (or C++) on a PC with some little emulated bits, then shove it on a sub $5 ARM. I can almost guarantee this is "cheaper" since the time investment will be lower than adding HuC6280 support to another compiler, and you get a PC version of the game for similarly low effort.
Hahaha ... you're right, that's certainly one option.
It may even be a sensible option.
But it's not the intellectually-challenging option. It's not "fun" (to me, at least).
The fact that the performance will likely be better is another plus.
Nintendo did it back in the day, and there's no shame in doing it now to ship a better product.
So did Sega with the Mega-CD and the 32x.
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If you just want to write a "game", and don't really care what it runs on, then there are plenty of options out there ... like Unity.
Oh, and I, personally, have no interest in doing a PC game. Been there, done that, have the polo shirt.
It's interesting (to me, at least) to try to push the old hardware and see what can be done.
I've quickly lost interest in modifying either HuC or CC65. They're too broken at a low level to ever get good results.
We'll see whether the SDCC guru manages to keep up his interest in adding 6502 support to that compiler, or whether that will fade as the difficulties mount.
He's already added support for a different architecture and maintains that port, so he knows
exactly what to do, and he has a much better idea of the potential difficulties than I do.
Whatever happens ... my time investment isn't likely to need to be that great, because there's no way that I can jump into that codebase and help, it's way too opaque.
As an alternative, morphping the NESHLA concept into a PCEHLA front-end for CA65 might be interesting to do.
There are so many compiler-compiler tools out there these days, that just reading in a program in C-style-assembler and then transforming it into standard-assembler, is a pretty simple project.
Then I could get to play with the CoCo/R parser-generator again. It's so much nicer that lex/yacc, and it already has a complete ANSI C grammar written for it. Just add the symbol table, shake it all up, put it into the oven for half-an-hour, and it's done. How tough could it be? (Famous last words!
)
But, it's a low priority at the moment.