The free-to-play games.
Phoenix is a popular shoot 'em up arcade game created and manufactured by Amstar Electronics (which was located in Phoenix, Arizona) in 1980, and licensed to Centuri for US distribution. Phoenix was one of the first full color arcade games, along with Galaxian, so at the time it stood out. Also, it has distinctive shooting sounds that have become very familiar to fans of the genre. Most importantly, the Phoenix mothership was the first video arcade game boss where the boss was presented as a sep