As part of this, have you implemented hot reloading via a DLL? If so, I'd love to hear how you accomplished it. I've implemented it myself on a project of mine, but I had to make some significant changes to druntime to get it to work. I also have to work under some limitations due to the way D handles things (for example, no using classes unless I am very cautious, since the typeinfo won't match after a hot reload. Additionally, I completed disabled finalizers, as they were causing crashes). I'd be curious to know if there was a better solution than the hacks I ended up with.
I'm also curious how you did the single contiguous block of memory. Obviously D's garbage collector won't let you do this, so I'm assuming you'd have to roll your own allocator and make some changes to druntime to intercept calls to the GC and use your own allocator instead?
In any case, as a fellow D game developer, this is awesome stuff!