Space Invaders is an arcade video game originally released in 1978 by Taito. The aim of the game is to defeat five rows of eleven aliens before they reach the bottom of the screen. The player controls a cannon at the bottom of the screen that can move horizontally and shoot laser beams straight up which could destroy a single alien. The aliens can shoot downwards, and three shields are placed at fixed locations above the cannon to hide behind. These shields are slowly destroyed by the aliens' shots until the cannon has no place to hide and must dodge the shots.