Tennis for Two

He designed the game within a few hours, after which he and technician Robert V. Dvorak built it over a period of three weeks. The game was displayed on an oscilloscope and played with two custom aluminum controllers. Its visuals show a representation of a tennis court viewed from the side, and players adjust the angle of their shots with a knob on their controller and try to hit the ball over the net by pressing a button. The game was very popular during the three-day exhibition, with players lining up to see the game, especially high school students. It was shown again the following year with a larger oscilloscope screen and a more complicated design that could simulate different gravity levels. It was then dismantled and largely forgotten until the late 1970s when Higinbotham testified in court about the game during lawsuits between Magnavox and Ralph H. Baer over video game patents. Since then, it has been celebrated as one of the earliest video games, and Brookhaven has made recreations of the original device. Under some definitions Tennis for Two is considered the first video game, as while it did not include any technological innovations over prior games, it was the first computer game to be created purely as an entertainment product rather than for academic research or commercial technology promotion.

In 1958, American physicist William Higinbotham worked in the Brookhaven National Laboratory in Upton, New York, as the head of the instrumentation division. Higinbotham had a bachelor's degree in physics from Williams College, and had previously worked as a technician in the physics department at Cornell University while unsuccessfully pursuing a Ph.D. there. He served as the head of the electronics division of the Manhattan Project from 1943 to 1945, and began working at Brookhaven in 1947, which focused on researching peaceful uses of atomic power. Once a year, the government research facility held an exhibition for the public, with one day each for high school students, college students, and the general public. The exhibition largely consisted of tours and static displays, with some attempts at making displays with "action", so for the 1958 exhibition Higinbotham decided to make an interactive display to entertain the visitors. While reading the instruction manual for one of Brookhaven's computers, a Donner Model 30 analog computer, he learned that the computer could calculate ballistic missile trajectories or a bouncing ball with wind resistance, and he decided to use this ability to form the foundation of a game. He later recalled his intentions were that "it might liven up the place to have a game that people could play, and which could convey the message that our scientific endeavors have relevance for society." Higinbotham designed a game that used an oscilloscope to display the path of a simulated ball on a tennis court viewed from the side. The attached computer calculated the path of the ball and reversed its path when it hit the ground. The game also simulated the ball hitting the net if it did not achieve a high enough arc as well as changes in velocity due to drag from air resistance. Two aluminum controllers were attached to the computer, each consisting of a button and a knob. Pressing the button hit the ball, and turning the knob controlled the angle of the shot. Originally, Higinbotham considered having a second knob to control the velocity of the shot, but decided it would make the controller too complicated. The device was designed in a few hours and was assembled over three weeks with the help of technician Robert V. Dvorak. While most of the circuitry was based on vacuum tubes and relays, the circuits to display the graphics on the 5-inch oscilloscope used transistors, then beginning to replace vacuum tubes in the electronics industry. Excluding the oscilloscope and controller, the game's circuitry approximately took up the space of a microwave oven.

Tennis for Two was first shown on October 18, 1958. The game environment was rendered as a horizontal line, representing the tennis court, and a short vertical line in the center, representing the tennis net as viewed edge-on. The first player would press the button on their controller to send the ball, a point of light, over the net, and it would either hit the net, reach the other side of the court, or fly out of bounds. The second player could then hit the ball back with their controller while it was on their side, either before or after it bounced on the ground. Hundreds of visitors lined up to play the new game during its debut. Higinbotham claimed later that "the high schoolers liked it best, you couldn't pull them away from it." Due to the game's popularity, an upgraded version was shown the following year, with enhancements including a larger (10–17 inch) screen and different levels of simulated gravity. Players could set the game to simulate the gravity levels of the Moon or Jupiter. Higinbotham referred to the game as Tennis for Two, though a placard attached to the 1959 version titled it "Computer Tennis". After the 1959 exhibition, the game was dismantled so its components could be put to other uses.