Just for fun, let’s find the different rules you can find in almost every eroge (or hentai manga, animes, …)
1 : If you have a stepsister => you’ll rape her (Hitomi)
2 : if you have a sister but not blood related (one of you is adopted) => You’ll do it with her (rape or not) (Crecendo, Kana)
3 : If you have a real sister, at least she will beg you to do it (snow drop)
4 : If you do it with your sister, sooner or later you’l discover you’re not blood related
5 : Never be nice with more than one girl
6 : Be nice to everyone and you’ll have the wishy washy guy ending (no sex) (Snow Sakura, …)
7 : If there is a minor character who is a man and has a dark glare, he will rape someone. (X change, Sagara family, …)
8 : most of the time “bad ending” means rape
9 : When the most important choice can have no effect on the game, something as minor as resisting to a girl who gives you a footjob can make her die (YMK).
10 : if there is a real ending to unlock after seeing the other endings, those endings will always lead you to the death of someone.
11 : no matter how stupid, wishy washy, evil, … you are, every (voiced) female character will fall in love with you.
12 : supporting male characters never raise their flag (or maybe with you… x change…)… except if they rape someone.
13 : gym teachers are rapiest (no exception)
14 : Only female characters need to pee
15 : Tey are never too young, old, rich, poor, dirty, … to do it.