The free-to-play games.
Space Invaders is an arcade video game designed by Tomohiro Nishikado, and released in 1978. It was originally manufactured and sold by Taito in Japan, and was later licensed for production in the United States by the Midway division of Bally. Space Invaders is one of the earliest shooting games and features two-dimensional graphics. The aim is to defeat waves of aliens with a laser cannon and earn as many points as possible.