Zoradius is an unlockable 3D remake of the original Gradius arcade video game found in Zone of the Enders: The 2nd Runner. It can be found in the battle against Vic Viper, or by replaying the fight as an Extra mission, then pausing the game an entering a variation of the Konami Code.
In Zoradius, the player uses the Vic Viper in fighter mode, flying through a tunnel and shooting down various non-humanoid enemies from the game to gather powerups to increase the Viper's firepower and shields. Roughly halfway through the stage, the player has to fight through an area full of ring-shooting Moai heads, also a staple of the Gradius series. The game ends in a Boss fight against the Train boss, also from the main game.