A great game! Especially if you're looking for an alternative to the Basic roleplaying system. In 34 pages, you have all you need to play in an hour horrific adventures full of tentacles. The rules are simple, but quite sufficient for this kind of campaigns. I especially like how the game manages sanity. In addition, it provides guidance on how to manage horror and investigations. What I like the most is that the author doesn't just copy the Old Ones and their servants, but he created his own vision of the mythos with very unique Old ones, several examples of cults, a revisited Dreamlands and some really vicious monsters. These chapters alone worth the purchase wether you play with these rules or not.
Its creator, Kobayashi, is definitely one of my favorite game desigers. His style is direct, effective, full of humor and innovative. He knows how to get to the core of what are roleplaying games (fun and excitement) without all the inconvenience of complicated rules. His games largely deserve to be known by all.