So, skills.
anal, vaginal, oral, strip, group, bdsm.
I figured we could use group along with sex skills, at very least because we will have more skills for items (=more ideas). During checks we could always use group/2 + (anal+vaginal+oral)/3 for example, or if we know what body parts are used in group, more specific formulas.
Bdsm could be splitted into domination and submission parts. Though we don't have many domination pics or events, so maybe not. It will help with items, but if skill will be useless, so will be items.
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refinement (general knowledge about society) and dancing. Moar in the future.
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service, bartending, cleaning and waiting. Yeah, we could use service as a general skill (like, experienced bartender will be not bad waitress either becasue she already has high service). More difficult checks too then, like (service+bartending)/2.
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For SE: leadership (better leader = bonuses to stats), exploration (chances to find something), stealth (chance to avoid enemies when hp is too low), traps (they will be in the future anyway, meanwhile could be used to capture monster girls).
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For ST we need at least two skills: skill that helps to teach and skill that helps to, well, dominate and enforce.