I really like the universe McAuley has created in his Quiet War series. It’s sizable (solar systems-wide) but it’s believable.
This last(?) book takes place thousands of years after the events in Gardens of the Sun. A mighty regime, the Empire of the True, has risen and fallen after picking a fight with artificial intelligences. The solar system is battered, in recession, and beset by superstitious cults. Our hero Hari sets off on a quest of vengeance, complete with maguffin, after his family’s ship is captured by sinister forces. Recommended.