The main character’s name can be changed in the beginning, but her backstory is set in stone. Thankfully, the replay value is through the roof. The game does feature a bit of action here and there, and not everything is about sex and relationships, but the focus is clearly on the demons and your character.
Seduce Me is a visual novel with dating sim elements and many possible choices, in which you get a chance to become romantically involved with an incubi, or a male succubus.
Hence, storytellers are probably not going to run out of ideas anytime soon, although for some reason many prefer to stick to classics like trolls, orcs and the undead. It’s hard to keep track of all the demons and monsters that have been imagined over the centuries, and even modern creations like D&D feature hundreds of creatures and variations on the theme.