Blue Heat is done, but it was with no shortage of annoyance that I had to ditch Retroarch for this particular outing. Frustratingly, the game itself works just fine in Retroarch, the issue is that disc-swapping, itself, doesn't currently work correctly in the DOSBox core. It technically works within a DOS setting, though it's unwieldy as you have to manually add discs to the swapper after loading the game - you can't do it beforehand like you can in standalone DOSBox - but, in a Windows 3.1 setting, swapping/adding discs just crashes Retroarch outright. I think this is likely the result of protected mode and the somewhat unusual way in which disc swapping is currently handled in the core which, unlike standalone DOSBox, essentially treats swapping discs as if you're replacing the entire drive with a new one that contains the new disc, rather than simply changing discs in the existing drive.
I would at least include it as an option if it weren't for the fact that the game stupidly requires you to start the game with the first disc, and only the first disc, even if the save that you're going to load is on disk 2+, which means that even if you were to swap out to standalone DOSBox to create a save at the start of the next disc and then switch back to Retroarch, you'd still never be able to use it in Retroarch because you have to start with the first disc no matter what anyway.
I had the bezel and shaders setup, everything looking great, managed to get it running well - which was harder than normal for this particular game - but after much wailing and gnashing of teeth I'm just going to have to bench Retroarch for this particular project for the time being. I've talked to Radius (the primary dev on the core) about it, and submitted a few issues on github for this and a couple other things, so hopefully it'll be ironed out in the future and I can add it back in at that point. For the moment, however, gonna have to be stuck with regular old DOSBox for multidisc 3.1 games. C'est la vie.
Anyway, I should have this out tomorrow. Just going to do some final testing on the package, write the review, etc.