To play as Falconess WITHOUT CODES, collect 50 coins in the Castle 
Treasury bonus round before time runs out. The portal to the bonus round 
is accessed by standing in front of the star-studded door that is near 
the end of the Castle Treasury level. Initially hidden from view, the door 
whisks players into the future - to a bonus round on a space station. 

Alternately, to play as Falconess WITH CODES, raise Valkyre to level 10. 
Then, at the character selection screen, hold Turbo and choose the same 
character. Valkyre will turn into Falconess!