Nice start, but definitely a start. Has boob sliders, 10/10.
The mention of Fallout Shelter is interesting. Could you give me some details about it?
I think one thing that might help is starting the story before the kidnapping, a prologue where you establish both of the characters. This would help with some of the clunky dialogue in the beginning. Depending on how ambitious you are this would be a good opportunity to establish some degree of character customization. For instance the player could determine the main character's sexuality(straight/gay/bi) and gender identity(male/transfemale/trap) which could in turn determine how the main character reacts to certain situations. I can go deeper into this if you wish.
As for content, it depends on how extreme you want to go. Ballbusting/castration is a big fetish of mine. Could be a fail state if you piss off your captor enough. Maybe a mode where you play as the captor? But maybe that's a separate game.
For some reason I had it in my head that you were going to make it similar to old school Zelda. So what you're going for is how you enter encounter's staying the same, it'll just be action based when you enter the battle.
Here's a thought- how about making it a bit similar to a fighting game? Blocking, parrying and whatnot. Think Soul Caliber.
Guess it depends on how far you want to go,