A loops and traps maze is more challenging than a standard box maze, because the doors are one way. You can only open them from one side. On the other side the doors represent a dead end. In this way, unlike a box maze, paths are created in one direction, but not in the opposite direction. This makes it impossible to retrace your steps for any great distance.

This kind of maze was part of many early computer programs. I remember one called "Cave" which had a version of this in the late seventies. The Ridgewood Halloween Maze in Ridgewood is the only one that I know of, which is designed for actual human beings to go through.

Although it is not apparent with the graphic you have included, the Ridgewood maze is even more difficult, because the doors can be very hard to find. There is a video of this maze (the 2010 version) Here is the link: http://www.youtube.com/watch?v=iHklXEho9Z0

One of the cheats in a traditional maze is that you can stick your right hand out and keep it on the wall. eventually this will lead you out. In a Loops and Traps maze, this will lead you in circles.

Now a free virtual loops and traps maze can be found here: virtualmaze.org