Sheep and Gates (1952)

A video game created by Stanley Gill and involved a dot (termed a sheep) approaching a line in which one of two gates could be opened. The Stanley Gill game was controlled via the lightbeam of the EDSAC's paper-tape reader. Interrupting it (such as by the player placing their hand in it) would open the upper gate. Leaving the beam unbroken would result in the lower gate opening.