How? Someone said something positive about this game and I decided to buy this to get the free shipping when I got Heirs to Heresy.
What? A sort of sandbox for building modern occult/horror games. There's one specific thing about the world: we are surrounded at all times by a dark Nether that tinges the world to some extent and maybe has little pocket dimensions. But everything else is pretty much up to you and your game group. You can play regular people who have been exposed to this darkness and now can't look away (maybe you seek to know, to kill, to protect, or to quarantine). You can play the monsters or people who embraced the shadow world (maybe you're afflicted by the power or devoted to something higher or a host to something alien or simply ravenous for something).
As you might expect from a sandbox style game, there's magic and supernatural powers that are sort of open-ended in how they're defined. Or maybe another way to put it is: let's say there's a magical attack power, but that will look different for a ghost or a vampire. In fact, the last third of this book or so is all about how to create your game: different tones or campaign frames.
Yeah, so? Don't get me wrong, the game isn't truly generic -- even the part about how to create your own game makes some assumptions (that there will be factions that you might get tangled up with). But it really does feel open-ended and interesting and... maybe if I had a game I wanted to run, I might turn to this, but I'm not sure what I'd run with it right now.
ETA: oh, I forgot, this book continues the tradition I've noticed in other Osprey RPG games of having too many copy-editing mistakes for a book that looks so nice otherwise.