Gradius is a side-scrolling shooter video game developed and published by Konami. The first game in the Gradius series, it was originally released as a coin-operated arcade game in 1985. The player maneuvers a spacecraft known as the Vic Viper that must defend itself from the various alien enemies. The game uses a power-up system called the "power meter", based upon collecting capsules to purchase additional weapons.

Shoot 'em ups are a sub-genre of action games. There is no consensus as to which design elements compose a shoot 'em up; some restrict the definition to games featuring spacecraft and certain types of character movement, while others allow a broader definition including characters on foot and a variety of perspectives.