I like a lot of this! Most of it is pretty cool, but there are some blindspots and some spots of inconsistent language that make me as an intersex person feel excluded.
Referring to sex as designated in its definition and not assigned, leaving descriptions of IGM as though they are neutral, and not something with a universally very high rate of regret among adults who grew up with the consequences of it, not mentioning the racialization or coercive nature of how our society sexes traits outside of their effects on gender when the gender and sex binaries are both socially constructed feels like a stark exclusion.
It also falls victim to something a lot of other western anthopologists fall victim to, flattening two-spirit into one identity rather than a result of the modern pan-indianism movement's recognition of a variety of pre-colonial roles which have been syncretized with colonial christian genders. As well as treating muxe and hijra as complete third genders desipte most of both hijra and muxer identifying also as women, and in the case of the hijra being socially identified as a third gender of infertile women. This is not my space to decry, but it should be noted third-gendering is often used as a tool of dehumanization and degendering especially to transfeminized populations in many places. My friend Moss is Lipan, and also a Changing Woman, which while being a two spirit identity, is just another face of womanhood and should not be excluded as such.
This book feels incomplete, I would love to bring a game like this to my friends and build a world together but I would have to rewrite so much of it I don't think it would be worth it. Good work overall, and I look forward to seeing the work improve.