In the game you play as a security guard for a Chuck-E-Cheese-like business, and find out after you're hired that the animatronics start moving once the sun goes down. You have to survive until 6 am, and you only have a limited amount of power to keep the lights on, cameras working, and doors locked.
This game is very interesting in that it utilizes psychology in much the same way as the original Silent Hill games. You stay in the camera room and can only flip between cameras, and once the animals start moving it becomes difficult to keep track of where they are through the static. Not only are the animals incredibly creepy, but you have to stay incredibly focused to survive. This focus is what drives the tension, and in the end can feel like you yourself are the one in danger.
TERRIFYING, but not much replay value. Worth the purchase for the original experience alone.