I'm also trying to write some visual novel games, for Ren'py. (If my text-based adventure games don't get picked up, I'll probably look into doing a visual novel port). Mostly, I'm writing Nancy Drew parody games, starring Francy Droo.
As it turns out, writing a straight-up parody is difficult. I spent about ten minutes thinking of ways to parody The Secret of the Old Clock, and the only joke I came up with is changing "the Crowley will" to "the Crummy will". So I scrapped the idea and made up my own girl detective instead. I'm still keeping the name Francine Droo, because it's awesome.
Mystery #1 is The Mystery of the Missing Mother-In-Law, where a mother-in-law is kidnapped on a wedding day. I want to give the game multiple endings, and my current problem is making it so the player can find all the circumstantial evidence on their own. It's a lot easier to force players to find evidence, but not as much fun to play.
Mystery #2 is The Midnight Phone Call. Francy changes phones, and she finds a mystery when she gets calls intended for the phone's previous owner. I'm not sure where I'm going with this, but I hope to have an ending where Francy goes up against a knife-wielding maniac.
Mystery #3 is The Speed Dating Sham. Francy goes speed dating and...um...somehow a mystery is involved. I like the title, so I'm keeping it, even if I can't think of a good crime.