Gradius (originally titled "Choujikuu Fighter Gradius") wasn't the first shoot 'em up to grace arcades with its presence, in fact many big names came before it. Space Invaders, Xevious, Galaxian, Ozma Wars, and even western titles like Asteroids and Defender all came first. So why was Gradius significant? Not only did it introduce several "characters" that would reoccur throughout the Konami universe (The very ship that you control called the Vic Viper, Moai heads, etc), but because it fleshed out the details of exactly what the average horizontal shoot 'em up would become: A game about strict power-up management, and pattern observation/memorization, and reaction. This may sound negative, but shoot 'em up fans (myself included) have long since embraced what the genre is, and they really have Gradius to thank for making it that way.