Adventures of Jimmy Neutron Boy Genius vs. Jimmy Negatron, The

Enter the following codes to enter the levels.

In a rush to go to Retroland, so you can go beat up your evil double! Then at the Main Menu when the ''Blue Neutron'' appear's on Jimmy's super computer, press down until Jimmy says ''Can I continue a game?'' Press A and you'll be taken to a code screen. All letters marked as (B), are circled letters.

Retroland and Jimmy Negatron (with full life and ammo)
DBD7M(V)GZ

This code will let you go through Retroland and fight Jimmy Negatron with 3 Jimmy Neutrons remaining, a full bar of life, and a full bar of ammo.