Something I just thought of, why is there no asphyxiation play in the game? For forced it could be a great way to build fear (at the risk of doing damage to the slave), but for consensual it could be a super kinki thing to do. Choking, ropes, all kinds of things could be done relevant to this. Also, there should totally be a "Safe word" mechanism implemented where consensual slaves with low obedience but high loyalty may use a safe word when doing kinki actions without proper traits, and ignoring it raises obedience but lowers loyalty. There should also be different types of "citizens" rather then just lone xx or traders. Sure their class after you catch them might be something, but I think having more repetitive mini encounters would be nice (I.E. lucky! you happen across a (insert race here) chopping down trees in the woods. Endurance and strength stats guaranteed to at least be 1. Harder to fight, but a guaranteed slightly rewarding possibility. Lucky! You see a (race) basking in the ocean as if a muse of beauty. Guaranteed at least slightly higher beauty and charisma. FUCK! You happen across a mad (insert race here) covered in muck from the woods, and they're ready to attack!)
Also a major standard in hentai-games: Why are there no tentacles fucking? Why can't a scylla player or slave use them? Why can't you get body modifications to get a tentacle dick? What do I have to do to get topped by 3 other dudes in a giant tentacle orgy over here?
More weird stuff: M-Preg through the use of potions or magic. Genitaless slaves or player, since some people got a Ken and Barbie kink out there.Why just kennels? Why not a stable, a common theme in zoo-topics also giving the possibility of riding horseback to save energy and traveling faster? Male breast lactation (if not already implemented). Cum-milking (works best on sex-crazy slaves). If you want to add really fucked up shit, lobotomies and punishment castration, as well as removing individual limbs (removes most job opportunities), as well as spawned enemies/individuals with missing limbs that lowers their value and is fairly rare (perhaps more common in places like Gorn, bandit camps, and the like). Also, why not have multiple dicks? It would require the lab, sure, but could be useful.
This is all stuff I thought of after a late-night attempt at finding whatever I was in the mood for, and failing miserably, so at least y'all can use this as reference material.