At the moment, I'm considering doing this thing up in three "chapters" or "parts", with each a reference to the Little Brown Books. Why do I insist on coming up with these overly-clever bits? Beats me.
Anyway, the first part would be called Species and Sorcery. But the actual content is still very undetermined. Once I get the Psi rules from James, that will help me flesh out the second half of the equation. But the first half is trickier.
I tend to prefer my games with nothing but humans nowadays. Oh, maybe the occasional Thark just to throw the humans into relief, but the whole interracial, Fellowship-thing does not much suit me anymore. So I'm very tempted to restrict Species to exactly one category--True Man. This would play up the idea that we are at the end of the run for Homo sapiens, as the last representatives of that paradoxical species battle their own creations at the terminus of the world.
On the other semi-human hand, there is so much scope for near-humans here. I mentioned this in the first post: Ultramen, Inframen, Pseudomen, and New Men. That's a lot of possibilities right there. Genetically engineered, mentally unbalanced Ultramen battling side by side with with organic android Pseudomen and the sentient descendant of uplifted Fossas? Yes?
The biggest problem with the second scenario is mechanical. I don't want to define all variations of uplifted New Men, engineered Hypermen, etc. Neither do I want to come up with any complex way of mechanically distinguishing them. One of the draws of the old-school game is that there isn't actually a heck of a lot of rules differences between the various "races". In my games, being a demi-human basically just means that you have the option to multi-class and a little trick or two (such a detecting slopes) in exchange for an XP ding (I don't use Level Limits). This isn't GURPS and there shouldn't be any complex system of exchanges that turns the whole creation exercise into a point-buy system.
But I'm not sure how I'd do those various Semi-Men otherwise. Well, something to ponder.