I've gotten it to Release Candidate. I...
It's... finished. At least, as finished as I can have it, for now. Finished enough! It has some really really basic meaningless issues, and also (for now!) lacks a custom nav mesh, but, it's done.
Of course it's plenty detailed, now. I don't think I changed much of the gameplay, though? Uh, I guess clipping is not perfectly one way or the other, but I hope I have compromised well enough on that... I can release new versions if that's much of a bother. Or separate versions. How wonderful.
But it's done. I've made it.
I hope it was worth it.