I get a warm, nerdy smile whenever people ask about books tied to games—there are so many flavors, from faithful novelizations to sprawling lore-expanding epics. If you want a classic gateway, pick up 'Halo: The Fall of Reach' by Eric Nylund. It's a novel that fleshes out the Spartan program and makes the sci-fi feel cinematic in prose. For narrative-driven RPG fans, Drew Karpyshyn's 'Mass Effect' novels like 'Mass Effect: Revelation' are great—those dig into characters and politics you only glimpse in the games.
Beyond those, there are strong franchise tie-ins that read well even if you haven't finished the game: the 'Assassin's Creed' novels by Oliver Bowden retell and expand on Ezio and Altaïr's stories, while S.D. Perry's 'Resident Evil' books are solid horror-thriller retellings and side adventures. If you like worldbuilding, 'World of Warcraft' novels by authors such as Richard A. Knaak and Christie Golden build entire eras that the games reference. And for something unexpected, Max Brooks' 'Minecraft: The Island' is a delightful solo-adventure novel that captures the game's tone in a standalone story.
I usually grab these at bookstores or on audiobook services—some of the narrators really bring the game voices to life. If you want recommendations tailored to a particular game or mood (creepy, epic, cozy), tell me what you like and I’ll point you to a few favorites.