Incest and Harem, but we’ve had a wave of such poorly made games.
Incest because of the payment methods.
Harem just for popularity. Any game that has sex with three NPCs gets labeled a harem. Harems where only the numbers matter, with no real reason for the girls to be with the MC, no romantic conquest, and no corruption path for them to accept sharing the MC.
I love me some management games, give me fun gameplay.
Also this one is not usually tagged, but you can find a collections and lists for it, i like the theme of "Sex Battle", especially with male protag, there are some amazing games with this mechanic.
Group-sex, I feel like anything else ive seen time and time before, but not nearly enough games have great multi girl scenes. Especially if paired with incest (bonus points for mother/daughter scenes!)