Unlocking Extra Suits
Unlock Black Costume:
Complete the game with a 100% completion.
Unlock Classic Spider-Man Costume:
Download and start the 'Rhino Challenge' DLC.
Unlock Cross Species Costume:
Complete the game on any difficulty setting.
Unlock Scarlet Spider (2012) Costume:
Find the fountain which is located near the middle of Central Park. Then, go north until you reach the middle bridge, which is directly at the center of Central Park. If you look on the right side of the bridge you will see a Spider-Man emblem. When you take a picture of the emblem the Scarlet Spider (2012) costume will become unlocked.
Unlock Negative Zone Suit:
Search on top of the Beenox building, second building inward from Brooklyn Bridge.
Unlock Future Foundation Suit
Search behind the gas station store in a small alley. One block right of north bridge.
Unlock Big Time Suit:
Search Times Square behind the red bleachers, on the glass.
Unlock Original Suit (No Belt)
When the game begins, you will have this suit. Go to Peter's apartment and check for alternate costumes. The original suit will be waiting in the closet.
Unlock Sam Raimi Trilogy - Classic Suit
When you register any of the game's DLC (including any pre-order code you may have received) and you will unlock this suit in Peter's apartment.