I got super curious about this after replaying 'Pathfinder: Kingmaker' recently and diving into its lore! From what I've pieced together, there are at least three official tie-in novels set in the game's universe. The first one, 'Pathfinder: Kingmaker—The Varnhold Vanishing' by Richard Lee Byers, follows the mysterious disappearance of a settlement, tying directly into the game's second act. Then there's 'Pathfinder: Kingmaker—Blood of the Ancients' by J.C. Hay, which explores the barbarian tribes and ancient conflicts. Finally, 'Pathfinder: Kingmaker—The River Runs Red' by Dave Gross kicks off the adventure, mirroring the game's early quests.
Beyond those, there's also the 'Pathfinder Tales' series, which includes broader stories set in the same world, though not all focus on the Kingmaker arc. I love how these books flesh out the characters and settings—especially the political intrigue and wild magic. If you're into tabletop RPGs or just enjoy high fantasy, these are worth checking out for extra depth. The way they weave game mechanics into narrative is kinda genius.