Unlock Hard Mode:
     Beat the game on Easy or Normal difficulty to unlock Hard Mode.

Unlock alternate ending 1:
     Beat the game on Normal to unlock an alternate ending.

Unlock alternate ending 2:
     Beat  the  game on Hard difficulty with at least a 'Regular' rank
to unlock an alternate ending.

Unlock the Blackbird Suit:
     Beat  the  game  on  Easy  or  Normal  difficulty  to  unlock the
Blackbird Suit.

Unlock the Papillon Suit:
     Beat the game a second time and get a professional rank on all 50
trials and in your overall rank to unlock the Papillon Suit.