Spacewar! (1961)

The PDP-1 mainframe was not designed to play computer games. Computer games were pretty much unknown in 1961. Then Steve Russell designed the first action-packed, graphics-based, shoot-'em-up game, controlled by the mainframe's front-panel switches. It was a hack, using the PDP-1 for a purpose it most certainly hadn't been intended for—and entertainment hasn't been the same since. Play it live today to re-create the glory.