Space Invaders is the earliest shooting games and was one of the forerunners of the modern video game.
The game challenges the player to shoot the wave of aliens that rain from the sky. As you proceed Space Invader and begin to shoot more and more aliens, the number of aliens increases accompanied with fast music raising the excitement level. Defeating the aliens adds up more loop of alien with increased difficulty and the game continues without an end. The more you shoot, the more is the number of points gained by you.