'm having a little bit of trouble of what people really want when it comes to them, because I'm making my own little visual novel (not a Kiss x Kiss one, but I'll get on that after I finish a few visual novels first). I would like to hear everyone's input on it.
In my opinion I prefer dating simulation with one or two interactive components involved, as a girl x boy game. Yaoi is OK, but I find that it is usually 18 and over age thing going on, and it's kind of embarrassing to play when my parents are around. Voiced is actually kind of refreshing, especially if you recgonized some words. Although there are very few seiryuus that I like in each game that I've played, except for Uwasa no Midori-kun series (most of their voices are boyish and in middle range, not varying too much, but enough that it doesn't hurt your poor ears!).
I tried thinking up a good plot for a kiss x kiss seirei gakuen doujin game, but I realized that most visual novels are kind of hard to pull off. Since it circulates itself around mostly plot and character. You really need to know the character in order to get the audience to enjoy the character and the plot/point of the game. And then there's the art, not much can be say there unless you get yourself an artist or that you are an artist.
Others who are also making a game with whatever engine (example: Ren'py, Novelty, Blade, Game Maker, etc), good luck and I wish you lots of success! (note: I'm working on my second game, it's called "A Bad Liar", the first game being put on a pause at the moment.)