It's been in stores for only one week, but Mirror's Edge (a first-person video game developed by Electronic Arts, Inc.) is apparently causing quite a stir. Literally. People playing the game have reported feeling dizzy and, in some cases, so nauseous that they vomit, writes Clive Thompson in his Wired.com blog, "Games without Frontiers."

Mirror's Edge, available for Sony PlayStation 3 and Microsoft's Xbox 360 (a PC version of Mirror’s Edge will ship in North America in January 2009), is set in a police state in the near future. The game has its players assume the persona of Faith, a courier whose mission is to deliver sensitive information, which requires a lot of leaping between rooftops to elude agents of the totalitarian government. Whereas many other first-person shooter games stabilize a player's vision as their characters perform, in Mirror's Edge, players can see their arms and legs pumping as they run, and their perspective is jostled when they jump, slide, fight or climb over obstacles. The action is reminiscent of Parkour, which involves a lot of running, hopping fences, climbing parking garages—anything to get from Point A to Point B as efficiently as possible. (Several examples are can be seen at the Parkour.tv Web site.)

Players may become queasy because of the game's ability to interfere with the body's "proprioception," which Thompson points out is "a fancy word for your body's sense of its own physicality—its 'map' of itself. Proprioception," he notes, "is how you know where your various body parts are—and what they're doing—even when you're not looking at them."

Mirror's Edge is designed with the "the correct kind of visual feedback (your limbs, in a fully interactive world) with the correct timing," Tom Stafford, a researcher and lecturer in the University of Sheffield's psychology department in the U.K., writes today in his "Mind Hacks" blog. The game hijacks one's sense of proprioception by remapping "your body schema so that you feel more fully that you are the character in the game," he adds. "When your character runs fast, you feel it is you running fast. When you character jumps across between two buildings and look down, you feel a moment of sickening vertigo." Mirror's Edge does this, he points out, not because of the game's level of graphic detail but rather because of the fluidity of the interaction between the game and the player.

(Image courtesy of EA)