It started out as a new video game concept but quickly morphed into a prototype with a far more practical vision; a haptic device to help the blind and visually impaired. Tacit is a wrist-mounted device which informs the wearer about the proximity of objects in complex environments, according to its creator Steve Hoefer. Ultrasonic sensors positioned at the front measure distances from one inch up to 10 feet (2cm to 3.5m), Hoefer says, while motorized rubber pads at the rear apply increasing amounts of pressure on the wrist as users get closer to an object. The original idea was rather different. Hoefer wanted to create a “dungeon crawl” game (a type of fantasy role-playing adventure set in labyrinths) that didn’t rely on vision. So he built a haptic headband complete with sensors and vibration motors. “One of the biggest and best criticisms is that it is very difficult for a blind person to build their own. I hope to address that in a future version,” he said. Hoefer has released details of Tacit’s materials, circuits and software on his Grathio Labs web site under a Creative Commons license to maximise feedback and hopefully improve the design.