Sorry for the double.
Cheese cake / darth kiwi. Check out this movie:
Memories by Katsuhiro Otomo.
the third film on the disk is called Cannon Fodder (of the 3 it's the only one that otomo directed himself).
It's the tale of a city, where the inhabitants and the city its self is totally geared towards firing huge guns at an unknown enemy.
It's a seminal piece of steam punk, and you should seriously checkit out!
I don't know if this could fit the story but to paraphrase the narrative of CannonFodder:
Mars has been at war with earth for an eternity.
Neo Venetia is the last remaining city, and it bristles with weaponry all pointed at earth. They've been shelling the blue planet for over 100years.
The thing is, it's been so long, that everyone does their job as a matter of course. In all honesty, most of the populace don't know if the adversary on earth even exists anymore, they just shoot.
So, the story could be that you are a rebel who fears the war is over, that it has been for 100 years, and that the aristocracy of Mars simply keeps the populace locked in a cycle of "hypothetical war", so that they can live the high life.
Your character makes a stand against this tyranny. You got options with the plot : is Earth still fighting, or are the incoming shells coming from your own guns, designed to keep you believing there is an enemy?
Ah whatever, I just got a bit inspired... ignore me.