Recs if you like The Quantum Thief (Jean le Flambeur, #1)...

Limiting this to fantasy/sci-fi, these are books where the MCs are locked up for most of the book or it's a crucial part of the plot. This can include magical prisons, cursed towers, institutions of sorts, and probably more!

sci-fi books about simulations!!

Protagonists and supporting characters who see and/or hear the dead / ghosts

science fiction exploring quantum physics. is the cat dead or not?

You've hacked the Gibson and snow crashed with Stephenson. Now it's time to scour the darker nodes in the net for deep cuts and hidden data dumps.