Continue game play:
Press Down, Right, Down two times, Left, Right, Up, Right at the title screen after losing all lives during game play. Note: This code may only be enabled ten times.
Press Up, Down, Up, Left two times, Down, Right, Up, 1 at the title screen.
Successfully complete the game. Press 1 at the title screen and choose the "Continue" option to begin at Level 00.
Hint: Increased weapon power:
Collect a number power-up weapon, then keep collecting that same number to increase the power of that weapon. Keep collecting yellow power capsules to increase the power of the primary laser.