SPACE STATION: SILICON VALLEY
On the Zone Select screen, press Down, Up, Z, L, Down, Left, Z and Down. You should hear a tone. Now enter any zone, then exit and return to the Zone Select screen. From this screen a hidden bonus game that's a cross between Asteroids and Defender arcade games will appear.
GO to the Bank Selection Screen and enter the Control Pad and button sequences to unlock all the levels in a given world. Or, if you need a breather, hold the A or B button while the DMA intro screen is playing to view one of two alternate sequences.
Up, Down, L, Z, Down, Up, Z, Down.
Up, Down, Z, L, Down, Right C, Z, Down.
Up, Down, L, Z, Down, Left C, Z, Down.
Up, Down, L, Z, Down, Left, Z, Down.
Up, Down, L, Z, Down, Right, Z, Down.