well you will have to choose if it is multiplayer, and how many players in game(don't try to do infinite, it's basically impossible and if you want to and no one shows up you will have to put in alot of effort, all for nothing, but you will at least still have the story.) and what type of game it will be, an rp/sim, a text adbenture, and weather it will happen before, after, during, or even in the same universe as the story, of course, it is a small story, so I imagine it to be in a simaler universe, but not the same universe as the story, you do you.