Unlock Extra Scenarios 
     To  unlock  the  extra sub-scenarios you need to complete certain
scenarios with certain ranks.

Unlockable:        How to Unlock:
Nightmare 2        Complete Nightmare 1 with an S or A ranking 
Dark Legacy 1      Complete Fall Of Umbrella 3 
Dark Legacy 2      Complete Death's Door 
Death's Door       Complete Racoons Destruction 3 with an S or A ranking
Fourth Survivor    Complete Dark Legacy 2 
Nightmare 1        Complete Mansion Incident 1