You can either use Steam via adding an exe as a non-steam game running proton or manage it seperately using something called Lutris. In my opinion its easier to use Lutris as you get more control over the options so look into it.
Thought I read at one point that the authors of The Expanse had originally intended it to be a gaming universe? Then they made it into a book series instead. Then it became a TV show. And now…
It was going to be an MMO. But they are really expensive to make and have small profits margins, and I don't think it got that far off the ground. I've never even seen anything like concept art for it.
Then it got turned into a book series, then that got turned into the TV show, and the game is a game of the TV show. The story in the books is a bit different and no one knows what the story of the MMO was like.