This is an excellent horror role playing game, focusing on investigation, survival and deep character creation. Forget long lists of skills, pedantic rules, or endless lists of equipment, which are common to other modern games which only pretend to support horror and instead thinly disguise narrative for a game (you know who you are).
Here you will find plenty of ideas on how to evoke horror atmospheres, and how to design characters whose motives and actions are ingrained in the resolution mechanics; this is a TRUE storytelling game! The GUMSHOE system makes relevant the decisions of the players after the acquisition of clues, not the acquisition itself. Rules are provided for psychic phenomena and for sanity, also.
The game only uses six sided dies (one die, actually) for all action resolution, which makes it ideal to teach to new players.
With this game you can run games based on personal or survival horror. I have done both, and it works very very well. The game works as an excellent toolbox for horror stories.
The only drawback is that there are some typos, and some missing rules text (which can be found on the Pelgrane website anyway); hopefully a corrected pdf will be issued.
A larger "bestiary" would have been nice (only two horrors are described), however it's very easy to create monsters and NPCs to suit individual campaigns.
So, if you want an easy to play, deep and novel horror role playing game, you have found it. And you do not need other volumes to play.
[5 of 5 Stars!]