Spacewar!

Written in 1962 by Steve Russell and friends at MIT, Spacewar! is the first widely-played video game ever made: two ships duel around a star whose gravity pulls every shot and every drift, with hyperspace as a desperate escape. It ran on a DEC PDP-1 costing more than a house, spread to every research lab with one, and set the template the entire industry followed. Two players only — one controller drives both ships. Press Control-Enter or Start once the paper tape finishes loading.