Now, in all the entire (real) world’s airports put together, the number of people who got into concourses by walking the wrong way through exit doors amounted to maybe one or two per year: not enough to hold the attention, or assure the vigilance, of even the most rabid T’Rain player. So the APPIS system now sweetened the pot by automatically generating fictitious, virtual wrong-way goblins and sending them up that tunnel at the rate of one every couple of minutes, every day, forever. Some balancing had to happen—the value of the rewards had to be tweaked relative to the frequency of wrong-way goblins—but with a minimal amount of adjustment they were able to set the system up in such a way that 100 percent of all the wrong-way goblins were apprehended. The total number of wrong-way goblins that had to be generated per year was about two hundred thousand—which was no problem, since generating them was free. The trick, of course, was that a tiny minority of those one-way goblins were not, in fact, computer-generated figments. They were representations of actual human forms that had been picked up by airport security cameras as they walked the wrong way into airport concourses. In reality, of course, this happened so rarely that testing the system was well-nigh impossible, and so they ran drills, several times a day, in which uniformed, badged TSA employees would present themselves at the exit and show credentials to the bored guard and then walk upstream into the concourse. In exactly 100 percent of all such cases, some T’Rain player, somewhere in the world (almost always a gold farmer in China) would instantly raise the Horn of Vigilance to his virtual lips and blow a mighty blast and rush out to confront the corresponding one-way goblin: an event that, through some artful cross-wiring between Corporation 9592’s servers and the airport security systems, would cause red lights to flash and horns to sound and doors to automatically lock at the airport in question.