It's hard to explain, because each server runs it's own custom version, but the basics are you create a character, choose a job aboard the station, and go about doing your job. But there are other forces at work, there are revoltionaries who will convert members of the crew to kill the heads, or a wizard or traitors that have set objectives to complete, or aliens will attack the station, and you have to survive, a rogue AI, ect. ect. You can go about doing your daily job, or you can bend and break the rules to do something great, or horrible. I'll post more later
Warning for Language: in a sort of mocking way, it sums up the game from the view of a crewmember