Rating: 4/5
As a warning: Horrorstor has some pretty gnarly gore, but the way its presented in the written form kind of makes it pretty tolerable; any attempt to adapt this would either have to tone it way down or be comfortable with some pretty gross body horror. If gore is a big issue for I'd definitely recommend against it.
Horrorstor is one of those books that grabs you because of the novelty: it's set in a haunted offbrand Ikea. I've read the Alternate Dimension Ikea SCP entry and was more or less expecting the same. And well it kind of is, but instead of relying on high level terror and neat ideas and details its more of a character focused horror/adventure ride.
Presentationally this book is simply fantastic -- the inner cover has an Ikea-style map and several coupons, and each chapter starts off with a page advertising an individual ikea product with a silly fake-Norwegian name. When the book starts going into the whole ghost of a Panopticon prison stuff, the products shown get turned into torture devices, which was a fantastic surprise I didn't notice until I'd almost finished the book. After the end of the book and the reveal that the store is bought out by a maternity company, all of the back innner cover is coupons for that store.
The book starts out pretty strongly with just feeling realistic -- the protagonist Amy is poor and desperately trying to hold onto the position she has. Along with that is a frustrating store with coworkers who are annoying in various realistic ways. With the tension set up and her motivations to transfer back to a better store and pay bills, agreeing to the setup that leads to the horror proper happening is pretty organic, although they do hold a seance in the middle of it which is kind of silly but even then there's justification.
This escalates into running and hiding from a horde of prisoner ghosts and an abusive warden who buried them. Since the ghosts are more or less mindless automata stuck in their ways he acts as the primary villain; the true-believer manager the protagonist chafes under kind of acts as a minor, human scale antagonist until things escalate to the violent and supernatural. This is the part of the whole character driven aspect of the book I think works -- he's kind of set up to be a villain but is deescalated by how little power he has and his fairly germane and understandable motivations.
Amy becoming motivated to both escape and return to rescue her kind of leads into the adventure part where she braves the internals -- there's a pretty strong moment of her trying to turn the ghost prisoners against the warden (which she does) but their two locked in their roles for their to be an easy resolution.
There's also a pretty striking scene where Amy is strapped to like, a chair of despair that pushes into her a bit of an oblivion of believing she's worthless, that her only purpose is to live in the station she's at, and giving up. This is kind of half of her big change, where she's worn down before finding purpose again by realizing someone cared enough to rescue her. The language and presentation of her interiority here resonate in a way that definitely feels like it's punching above it's weight.
I think the thing that really made this work is that escalation, and that the finale of the book is followed up by an open ended epilogue where both the protagonist and her former manager decide to brave the store to rescue their lost coworkers, and that really leaves a good taste finishing it.
I had a blast reading this over an evening with a beer, and I'd definitely recommend it aside from the gore.