Just be careful writing when it’s inspired by a pre-existing game/story. If it comes out sounding too similar to Ace Combat you run the risk of being disqualified or losing based on the fact that Choice of Games, LLC cannot publish games which infringe on ‘Intellectual Property’ rights.
My advice, in terms of writing, is to first write down what scenes you already have planned or want to happen. People often focus too much on beginning, middle, then end. But what I personally think works best is to write those scenes you really are excited about then figure out how to get the players to that scene.
Oftentimes the scenes you really want to write have already been fleshed out in your head. You can write those down first to get them out of the way and then while you bridge the gaps between those scenes then you can revisit and rewrite them if necessary.
That’s all for my advice, good luck with your writing!