Level Select 
     Beat  the  boss  at  the  end  of  Stage  Nine to acquire the Map
Selector,  which  allows you to choose to go to a Stage you've already
beaten.
 
New Enemies in Old Levels 
     To  replace  the  same  tired  enemies  you've already faced with
slightly  fresher  baddies,  beat  the  Stage  Ten boss. You'll unlock
Change Appearance, which changes the enemy types.
 
Play as Arcia 
     Beat the game once to play as Arcia.
 
Unlock Hard Mode 
     Beat the game once to unlock Hard Mode at the difficulty menu.
 
Unlock Super Mode 
     To unlock Super difficulty, beat the game on Hard.