Well, thats kind of game that I was looking for. Main issue about what I can see is too plastic looking characters. Especially if you would go for VR it will be bad.
If you are going for this kind of games I recommend you to check Skyrim modding regards to that, SD+, zaz animations, how Immersive first person plugins enchance the gameplay, what kind of animation might look good etc, the way they are treatind bondage devices like blindfolds.
What most of these mods lacked? Progression, sexual lvling, interesting bondage gameplay mechanics, things to do between sex animations. This kind of games needs to immerse you into feeling that you are in a body of this character so you need to think how to make activities look realistic and well paced. But at the same time people might not be interested in some mechanics, like featured "pee controll" you might give an option to disable it for people not wanting this part of the gameplay in the game, same with fetishes and things like that.
Also if you are sub that doesn't mean that game should be easy. You need to be able to fail if you are not doing things right.
What about actual "sex" gameplay? I think it would be awesome if you would have a somewhat controll during sex scenes instead of having an observation of animation. Like you was given a task of licking the boots of mistress. And your game turns into first person (would be amazing if you could see certain bondage gear pieces like IFP mod that i've mentioned is doing and things like hair, maybe even partly transparent nose texture) and moving around with arrows to clean the shoes. And if you are somehow restrained and the process is very problematic - you keys will be reverted.
What you can do during "free time" when your mistress is gone? You could have simple chores with minigames, maybe you could learn some art and slowly learning to draw to draw your mistress and please her by worshiping her with your art, ways to train yourself druing freetime. I kinda not sure what type of gameplay will be apropriate for situations when you are locked in full bondage/restrained but it would be awesome to have things to do while being in this situation.
Having certain rules/phrases/poses that you 100% of the time should follow unless you will be punished might be a good idea. Close to the endgame it might be cool to have "extreme" transformations happening to you, like turning you into a permanent latex sex doll and having all the gameplay highly altered because of that.
With more inofrmation in place how it will be all going and working and especially with playable version more reasonable feedback will be possible.
p.s. Looks like some of these ideas actually is going to happen anyway, i've checked your blog.
