Alien Destroyer

Alien Destroyer is a 1-player Space Invaders variant for the BBC Micro.

The player controls a spaceship at the bottom of the screen that moves laterally left and right and fires vertically. A large group of alien vessels move horizontally to the edge of the screen, move down one row, and reverse direction. There are three large shields to protect the player from incoming alien fire. The player tries to destroy all enemy vessels before they reach the bottom of the screen. The player loses a life if hit by enemy fire. New walls appear every level. An alien mothership crosses at the top of the screen, and can be destroyed for bonus points. The player starts with three lives, and gains a new life every three levels.