William Higinbotham and Robert Dvorak, Sr. show off a tennis simulator game they called Tennis for Two. Developed on a Donner Model 30 analog computer using an oscilloscope, it is the first known electronic game to use a graphical display. Higinbotham and Dvorak developed the game to show off to visitors to the Brookhaven National Laboratory where they worked. The game was only shown off twice, during the laboratory’s annual visitor’s day. While hundreds of visitors lined up to play the game when it was made available, little was known about the game for decades. While somewhat similar in gameplay to the later hit Pong, there is no known direct relationship between the games.