If you take a look at its platform, format, and content, Corpse Party: Book of Shadows might just have the tiniest demographic known to gaming. If you'd like to play and get the most out of this semi-sequel to XSEED's surprisingly harrowing release from late 2011, you'll need to A.) own a PSP (or a Vita), B.) have some interest in visual novels, and C.) know the original Corpse Party fairly well.

But really, "C" makes for the most important factor; true to the original's dojin roots, Book of Shadows exists as a fan game of a fan game. Where the first Corpse Party tapped into the creative power and twisted imaginations of a small enthusiast team for one original and gripping thriller, Book of Shadows warps its predecessor's narrative to create alternate, episodic scenarios featuring twists and payoffs that only veterans of the original will find rewarding. Because it's so reliant on its predecessor for meaning and context, it feels unfair to give Book of Shadows a standard review; to be honest, the game comes off more like a bonus disc than a standalone release. But I can at least try to provide a fair evaluation informed by Book of Shadows' complete reliance on its source material -- that is my job, after all.

Book of Shadows opens with a playful take on some early events of the first game -- well, as playful as Corpse Party can be, anyway. After a prolonged intro featuring the mundane, pre-horror lives of two female protagonists (an approach that will return more than once), this duo finds eventually themselves trapped in the otherworldly school of the original, but with one important difference: like the player, one of the characters finds the scenario unfolding in front of her a little too familiar. Book of Shadows' opening plays upon your own fuzzy memories of Corpse Party, as both you and the protagonist desperately try to remember past events so they can't be repeated.

It's a great conceit that couldn't sustain an entire game, which is probably why it doesn't; instead, the remaining chapters take a fairly straightforward approach, and while they do offer their own twists and alternate takes on the story thus far, understanding the value of these episodes requires intimate knowledge of Corpse Party lore -- I played the original a little over a year ago, but still had trouble figuring out why some of Book of Shadows' reveals had any significance. That said, a good deal of Book of Shadows' content doesn't feel significant at all, as many chapters open with tedious, lighthearted anime teen antics that don't add much to the story other than getting to spend time with the characters outside of the hopeless situation that Corpse Party eventually drops them into. And since one of the biggest draws of the original could be found in how the characters changed and reacted due to the horror surrounding them, watching some chaste, Twilight-style high school romance play out over the course of an hour will have you wondering if you accidentally loaded up the wrong game.

Book of Shadows' change in perspective marks another departure from the original, and while this new first-person view feels more in line with the visual novel genre, it tends to slow down navigation more than necessary. As with the original Corpse Party, you're often left to wander the haunted hallways until you stumble upon the next event, but Book of Shadows can make this simple task into an agonizing crawl; instead of moving around a zippy little sprite, you travel through the environment space-by-space like a piece in some sort of demented board game -- not the worst idea in the universe, but travel is rarely speedy when each of these tiles has to load separately. Given that most of the game play involves stumbling upon the next terrible thing that might kill you, I would have appreciated it if Book of Shadows had more of an on-rails design; freedom can be fun, but staring at the same empty hallways for minutes on end certainly isn't.

It's tough to recommend Corpse Party: Book of Shadows, but equally difficult to condemn it. Yes, I probably would have gotten much more out of it had I played the original immediately before, but that's a pretty steep requirement just to get some basic enjoyment out of a game. And while I appreciate the fact that the game's violence doesn't pull any punches, and sells most of its horror through words alone, at times, it feels as if the blood and guts are meant to titillate rather than horrify -- and Book of Shadows' brief collection of panty shots (which are often determined to show you the tiniest sliver of white cotton) often make the experience more nauseating than intended. But if you fit into the very specific audience this game caters to, Corpse Party's stopgap sequel contains the horrifying scenes and unexpected turns of the original -- just make sure you know what you're getting into.