Game idea?

I'm taking a Video Games class at college and we're using twine to create our own games in class. I'm so intrigued and want to make a mind-blowing game.

I was thinking that I'd take inspiration from things I've seen around, like that old tumblr thing that suggested birthmarks are how you died in your past life.

I was thinking of creating a story where you hear somehow that is true for some, and with your unique mark, you wonder if this is true. You set of to try and find out, but eventually stumble across the truth of who you are: an angel killed by another angel.

I don't know how to flesh it out, any more details, etc. Since I just figured out an idea today. Thoughts?