Part science fiction, part weird necromantic fantasy, Gideon the Ninth feels like an actually readable version of Gene Wolfe's Shadow of the Torturer. And I loved it.
It reads in much the same way a good video game feels to play. There is deep but accessible lore, a cool magic system that can be exploited differently depending on a user's culture and genetics, and of course a God-King that everyone serves called The Necrolord Prime. The crux of the story is that this very Necrolord is in need of new Lyctors, powerful and immortal servants to help him carry out the duties of his death empire. Nine necromancers and their cavaliers, one pair from each of the 9 necromantic houses, must vie for their right to call themself Lyctor by solving a series of magic puzzles in a weird old house with skeleton servants and spooky danger.
In this book, Tamsyn Muir attempts to cut to cut through both tension and tedium with humor and for the most part pulls it off extraordinarily well. There are some genuinely funny moments. I loved the relationship between Gideon and Harrowhark, two extraordinarily well-written characters. It was deep, it was thoroughly explored, and it felt real. And for what it's worth, this is true of most of the other characters as well, and the cast here is significant.
This book came to me at a particularly stressful transition time in my life and dipping my toes into this awesome world at will was a real treat. There are more books in this series and I intend to read them, though I admit I will take a little break as a meander through some of my backlog.
All in all, Gideon the Ninth was fantastic. Highly recommended.