Don't get me wrong, I just LOVE Power Vacuum. Top 3 on my list.
I just ran into FOTM recently and found a lot of gameplay and story elements similar to PV(ie. mom telling daughters to do the dishes after meals, MC has erection problems that need to be addressed imediately, new girl joins and shares room with MC).
I agree massive grinding is required and it gets frustrating. I'm just hanging on to it because of the similarities. It almost seemed like PV is FOTM with all the cons ironed out.
They definitely share a sub-genre. "Suburban Oedipal Power Fantasy" I think someone called it in something I read, somewhere or other. Probably here, maybe check the reviews. Whatever it's called, it represents a pretty big proportion of lewd VNs. And its tropes are numerous and weirdly particular, like a scary older sister who's always raven haired.
But the similarities are surface level. Even putting aside its satirical aspects, the gap in writing quality between Power Vacuum and the rest of the... whatever you want to call the genre, is like the difference between Tolkien and the rest of Fantasy. There's PV up there with, like, actual books - then a sharp drop to the small-but-still-larger-than-it-has-any-right-to-be tier of porn VNs that also genuinely work as fiction - then a looonnng way down to the jumbled heap of good-atrocious just-porn representing the rest of the medium. Unless FotM has changed a lot since I played it, I'd place it somehwere in the upper third of that general pile.
