The one thing that Athanor is missing so far is Earth men. After all, my big influence here is from the thread of fiction known either as sword and planet or planetary romance. Earth men are big in the genre, whether it be John Carter, Esau Cairn or Tarl Cabot (bonus points if you know all three references.) But while the importance of Earth men as point of view characters is essential to the sort of travelogue style narratives of much of the genre, I'm not so in love with those elements in the context of a role-playing game.
Part of the issue is that Earth men almost always outshine everyone. John Carter is superhuman in almost every way; Flash Gordon unites a planet when no one else can; Adam Strange is a better scientist with his archaeology training than any Rannian science academy graduate; Esau Cairn is the tougher than anyone on Almuric... the pattern is pretty clear. Even if we include Earth men, this seems hard to include in the game. We also need to deal with the fact that Earth men become alien and as such attention hogs in the game. It's hard for Earth men not to become the center of plots, reactions, and activity. And despite the current logic that lack of game balance at the table disrupts fun, I find that the thing that really disrupts tabletop fun is not game balance issues, it's screen time balance issues. A game where a subset of PCs get all the good attention is riding the rails to disaster.
I also don't want Earth men because then I will probably need to firmly declare where Athanor is in human history: past or present. And I will need to deal with questions of brining in other humans, dealing with reinformcements, interactions and travel between Earth and Athanor, connections between Athanorans and humans, and deciding whether all these Earth analogs in language and culture are really there or just abstractions to make the language and tropes make sense. I like doing a lot of hand waiving right now. Earth makes me have to make some decisions and stick with them.
Finally, I don't want the plot of the game to be about the motion of the Earth humans among alien cultures and creatures. That narrative, while interesting, is (in my totally arrogant opinion) the player's journey in interacting with the culture. I think Barker understood this in Empire of the Petal Throne. While he suggested that characters begin as barbarians to facilitate the idea that players were going to be learning about the complex cultures of Tekumel in the process of play, he didn't suggest they be from lost Earth. That would muck with too much in the setting, and (in my mind), muck with immersion. The Earthling heroes of planetary romances are already too much like Mary Sue characters to begin with. Using this trope with RPG planetary romance would be, it seems to me, a bit too much.
Now all I have to do is figure out how to address the common trope of the Beautiful Space Princess in Danger. On the one hand, I feel like I really need my own Dejah Thoris for at least one of my Athanoran adventurers, but I also think I need to make my version an interesting and competent character in her own right....