Well, what I like the most is very niche-y, unfortunately.. So, from more common to least common:
- Spanking (not the occasional slap during penetrative sex)..
- Commonplace Femdom (?): Not leather and whips, and revers-50-shades' female characters with mental issues-- Just ordinary, likable women with dominant personality that includes sexual acts, and power dynamics' relationships.
- Male Bisexuality (how is this a fetish, though?): I'm a firm "believer" of the banana-apple theory (most people like both, with a minority only liking one, and even a smaller minority liking neither; i.e. Most people are bisexual to some extent). I think the entire "futa/trap/femboy/..etc is not gay, bro" argument, only delays that realization, (you won't find a female counterpart that says: "bodybuilder/butch/tomboy/androgynous..etc is not lesbian, sis".
- Female Polyamory: I can only search for this as NTR, or Cuckoldry for some reason! It's really quite perplexing that even if the game has some male bisexual content, then the potential male interests are free to share, but the potential female interests are an exclusive property of the MC (unless shared with other female characters, because it becomes coveted then as "hot lesbian action" awaiting the male MC's involvement!)
So, something like "I Roved Out in Search of Truth and Love" but in a game format!