i know you probly dont want to do this but how about cock sizes with larger sizes aka horse size dicks being able to break a mates mind or alt make them addicted to it broken will make the mate useless mentaly and phy but addicted will make them fully loyal to the cock size if your master has that size they will continue to be loyal as long as you fill their loyality with your cock oh i mean their holes with your cock ^_^
this could also give some leanings to maybe some of the girls are kind hearted others rude af depending on their backgrounds they might try harder if their a kind heart because they dont want you to feel bad if your under the avg for your race but if your over the avg they will remark about how they like its size
another cool idea would be to add in a small dick mode where the goal is to breed many people but to do so you must grow your cock theres a few ways to do this
defeat a invader personaly
breed a mate
buy a potion that costs you like 9000 gold
or submit to the invaders and hope one is either horny and wants to r you or hope they have the rapist trait that will make them see you as lesser and do the deed with you