Virtual reality
The 1990s saw the first widespread commercial releases of consumer headsets. In 1991, Sega announced the Sega VR headset for arcade games and the Mega Drive console. It used LCD screens in the visor, stereo headphones, and inertial sensors that allowed the system to track and react to the movements of the user's head. In the same year, Virtuality launched and went on to become the first mass-produced, networked, multiplayer VR entertainment system. It was released in many countries, including a dedicated VR arcade at Embarcadero Center in San Francisco. Costing up to $73,000 per multi-pod Virtuality system, they featured headsets and exoskeleton gloves that gave one of the first "immersive" VR experiences. "Computer Gaming World" predicted "Affordable VR by 1994".
Ivan Sutherland
From 1965 to 1968, Sutherland was an Associate Professor of Electrical Engineering at Harvard University. Work with student Danny Cohen in 1967 led to the development of the Cohen–Sutherland computer graphics line clipping algorithm. In 1968, with his students Bob Sproull, Quintin Foster, Danny Cohen, and others he created the first head-mounted display that rendered images for the viewer's changing pose, as sensed by The Sword of Damocles, thus making the first virtual reality system. A prior system, Sensorama, used a head-mounted display to play back static video and other sensory stimuli. The optical see-through head-mounted display used in Sutherland's VR system was a stock item used by U.S. military helicopter pilots to view video from cameras mounted on the helicopter's belly.