Atari's 1980 arcade game Missile Command requires the player to defend six cities.
The cities sit along the bottom of the screen while enemy missiles descend from the sky. The player fires anti-missile shots from a central base, attempting to destroy incoming warheads before they reach the cities or the launch installations. The cities are essential to survival because losing them reduces the player's remaining defenses.
Missile Command was designed by Dave Theurer and released by Atari in 1980. Its cold-war imagery reflected contemporary fears about nuclear attack, although the game presents the conflict through abstract radar screens, missile trails, and explosions rather than realistic combat.
Players sometimes remember the number of missile bases rather than the number of cities. The standard game includes three missile batteries and six cities. Ammunition is limited in each round, so careful timing and grouping explosions are central to the strategy.