>>713725243
The second one sounds pretty good and the theme could easily be substituted into other settings like a fantasy one with goblins, slimes etc if a wider appeal is needed.
Either way I'd add buildable training rooms to the base which can be stocked with enemies or equipment to provide access to H-scenes/animations. If you leave a girl in there and go on a mission when you return she'll have gained a buff or skill, potentially with some downside, as a H-themed alternate to the main meta-progression.