hmm, I got a nice idea:
how about making a puzzle-game where your answers determine how the story goes. So you have a storyline and at certain points you have to give certain answers or solve a riddle and based on how you do it, the story evolves in different ways. It's different then most other puzzle games as the intention here would be that every answer is correct, it simply gives you a different ending. And if you can, maybe you can try and have it be based on personality/Zodiac signs.
Good luck and when you have it ready, please let me be the first tester