Missile Command as guessed by Darashiva
'Missile Command' is an old but famous arcade game later ported to various consoles in various forms, including the Atari 2600. I have played a host of these clones on almost every platform known to man alongside the Atari port, and I'm including this port as the representative of all of them. I have played one where the cities were more than just a bunch of pixels, ones where the cities look like London, New York, Tokyo and more, one that's on the moon, one with different types of ammo and one that includes Bill Paxton's line "Game Over man, Game Over" from the movie Aliens upon defeat.
The premise is simple, and I take it everybody knows this. The player must defend the cities below from aerial bombardment, carried out by aliens or an enemy airforce, by firing missiles at the incoming projectiles. The tips are the target, shooting the lines is pointless. Once a set number of incoming missiles are deflected, the player advances to the next stage which either ups the speed or amount of new missiles. The game ends once all the player's cities are destroyed.
These types of old games are always fun to play, even if only for a short time. 'Missile Command', 'Chopper Command', 'Pitfall', 'Asteroids', 'Space Invaders' and 'Pong' itself, you name them, I'll play them any day.