Video Game Project

As I am working on my project, I ran into a mental block. I'm trying to make the story for my game very dynamic and I can't get my story to flow from my opening scene that I made over the past week. I like how it's going, but I don't know where to start the next scene at. I am trying to figure out if I want to start it from before he joins the gang or start it from when he is already in the gang. I figured out what my main gangs in the gang are going to be, now I am trying to figure out what are they going to look like. The five I made have a nice backstory i made, but incorporating them into the story is a lot harder than I thought it would be. I'll post more when I think of some more to add.