I like the fact that your character is not a 100% slut from the start - far too many games make the heroine the town bicycle from the start without rhyme or reason.
If there is a need to unlock the "ho" side of her, well that's some extra quests and story content that players would likely appreciate. Btw, What game engine are you going to use?
Since you are asking about the game's mechanics, I might as well spill the beans. The concept for my game so far is this:
TLDR My game is about wooing Gwen while trying not to get cucked by a Gremlin, unless that's what you want to happen. It's a weird idea I know, I don't think I've seen a game try to cater to NTR lovers and NTR haters at the same time. It's also unique in the sense that you could if you want to play the game so that the only erotic content is implied sex.
So to answer your first question, sexual tension is a big part of the game. Meaning regardless of path
the scenes will start off neutral, gradually go softcore, then get more hardcore as the game progresses. Since Gwen will probably be the only female character in it, a lot of the story will be focused on her gradual shift in personality and relationship.
BUT if you read the whole concept you will also know that to actually win over Gwen there will be some challenging gameplay segments you need to master as well.
In terms of game engine,
GameMaker Studio 2 is the one I am most familiar with, so I will go with that to start. However, since that engine may not be entirely friendly towards ero games, I will switch to Godot or Unity if GMS2 gets fussy..
When it comes to progress, since my original post I have written a good amount of dialogue, and I've also worked on some more concept art. But everything is still in pre-production, no actual work on the game yet. The game mechanics will be relatively simple, I suspect the main bulk of the time spent will be the artwork. If I can I will try to make the art semi-animated too. Outside of the combat-puzzle gameplay it will mostly feel like a visual novel.