Humanity has never developed FTL travel. Every flight is made monotonusly, over dozens of years. This also means that the ships are inherently gargantuan to haul as much as possible in a sigle go.
The Ship your character on is an ancient decomissioned cargo hauler, capable of carrying nearly endless ammount of cargo. Or to build a city inside of it.
It was bought by a christian cult (or sect, it not exactly specified) which wanted to escape the "merally decaying Earth" and fly towards a planet, designated as habitable.
About 50-100 years into the journey there was a twist- they got the detailed photos of the planet surface from the deep space probes. And they saw small villages on the surface. Native sentient life, which by the time the ship gets there will be in about late medieval- early renaissance.
And the problems ran deeper even. Because christian fundamentalists didnt have that much money the ship was refurbished and supplied on the cheap. The crew was supposed to build colonial equipment during the flight. Not to mention cramped space and nessesity of hard work to keep the ship afloat. Their destination might have been a paradise, but the vessel was anything but.
The society was separated into rulling class (religious leaders and the ship's crew, capable of controlling the space leviathan, their security and the poorer workers). Tensions build over the years as the elites were living in relative luxury (think tine appartments and sometimes artificial meat and hydroponic vegetables) and the workers lived in dystopian factories (think sleeping pads and the disgusting nutrition pills 99% of the time). The revolt happened, followed by the civil war which lasted for about 30-50 years. As the sides battled each other their goals expanded and changed and now its a one big stalemate.
The ship is in the shit state, ship control and mission control decks have been melted into a big mess by the war, hydropinic desks have been neglected and turned into deadly toxic jungles, security is a death trap of automated security.
So this is where the player character lives- in a mess of shipping containers, in a tin can which might not even be on course anymore, where every day is a battle.
Christianity and religion play a noticable place in the story and its refreshing to see developers not holding back their creativity.
