Centipede

Centipede is an early attempt to bring Atari's arcade game with the same name to a home computer. The player controls a laser base at the bottom of the screen and has to shoot at the centipede-like aliens that appear at the top of the screen and then crawls towards him. Unlike the Atari game, the player can only move left and right and not up and down. Neither does it feature any mushrooms. Instead, there are only a few obstacles that stop the centipedes and make them change direction. When a centipede is shot, it splits into two halves. The player must shoot all segments before they reach the baseline. If they do, the player loses a base. The number of bases is user defined (1 to 5) and so is the movement speed of the centipedes. Another feature not present in the arcade game is that the centipedes can drop bombs at the player.

It's historically significant as this was Jeff Minter's very first commercial release.