Gradius is a single-player and multiplayer action, shooter, casual, and arcade game in which players control the Vic Viper spacecraft to combat an alien invasion. In this game, the storyline revolves around the planet Gradius, which is threatened by the Bacterian star cluster invading from subspace, prompting the deployment of the super-dimensional fighter Vic Viper to destroy the enemy fortress of Xaerous. It stands out with its innovative use of a 'power meter' system, allowing players to select and activate power-ups strategically during gameplay, enhancing the classic shoot 'em up experience with advanced customization and gameplay depth.