Tachi: Japanese slang word for the "top" or active partner in a relationship. Neko: Japanese slang for the "bottom" in a relationship.
These are terms used in the Yuri community.
That's very true, personally the only good western game that always comes to my mind are the ones from evakiss.
When it comes to female protagonist japanese eroge, only a few of them are really worthwhile, and unfortunately almost all of them are not officially translated.