Pantyhose. Not only does it not appear enough in games, but when it comes to the sex scenes, it's always an afterthought and therefore never treated as a fetish. Either the pantyhose comes off before the sex happens or a hole is ripped through them before penetration. I like the latter much better than the former, but I've yet to see a single porn medium--never mind game--handle it in the way that I'd like to see.
I want the girl and her partner to derive pleasure and orgasm from the feel of the pantyhose--especially those which are sheer-to-waist and seamless. If the partner is a guy, then I'd like to see him kiss the girl's legs, run his hands along them (both initially and during sex), and hump her leg. If the partner is a shemale or another girl, then I want to see the same things with the addition of their pantyhosed legs rubbing together while they're in an intimate pose. Regardless of partner, I'd like to see the girl's pussy being licked at and rubbed by a tongue or being devoured. When it comes to penetration, I want the pantyhose to remain intact, having the girl(s) be fucked by the layer of pantyhose stretched over the dick or fingers that are penetrating her. If the partner is a shemale, then that would be two layers of nylon.
Most importantly, I want to see the girl(s) getting off hard specifically because of the pantyhose enhancing their partner's (or her own) manipulation. I'd love to see partners cumming through the pantyhose. The girl cum be thick and creamy on top of the nylon as the fingers are removed or the guy/shemale can blow his/her load through the pantyhose while fucking the girl. With lesbians, I really want to see the nylon wet to the point of transparency as they trib and then have their thick cum create a nice pool between their pussies.
I don't have a fetish for the guy wearing pantyhose or men's pantyhose, but I don't oppose it. Also, if the partner is a shemale, then she can wear either type, too. If hers is a normal pair, then I'd love to see her pitching a tent in them. When going for penetration, she can grab the pantyhose at the base of her cock and position herself accordingly.
To make it even more erotic, the woman/women could be wearing bodystockings. As it's a game, they can also be sheer and seamless. Breast play would be a definite plus in this situation, whether by hands or mouths.