The Guts World is an area that can be accessed from the Intestines Maze or the Visine World.
Features
The Guts World is a fairly large, empty area. The only notable features are the random organs scattered about and the odd black walls with pink outlines, some of which have odd, white beings trapped inside of them, which are all inaccessible to the player. (One serves as the entryway from the Intestines Maze.) Otherwise, this is a big and empty area with nothing particular in it.
You can chainsaw some of the guts on the ground, but this does nothing. If you find the giant, white spider-looking thing, you'll be teleported to the Intestines Maze.
If you find the large, floating... thing and walk under its shadow, you'll get sent to the Visine World.