Type At The Title Screen:
rush (silly ships, THIS DOESN'T ALWAYS WORK!!!)

Type At The Main Menu:
xteam (gives you Pirahna Team)
xtrack (gives you all tracks)
xclass (gives you the Phantom Class)

Type At The Pause Screen When Playing The Game(the Esc button):
psymega (gives you infinite weapons)
psyticker (gives you unlimited time)
psyprotect (gives you infinite energy)
psyrapid (gives you a machine gun)

Type Anytime During The Game:
framerate (displays the frame rate)