The following costumes are unlocked by completing the corresponding task during game play.

Unlock Masked Sam Costume:
In the Penthouse level go to Zherkezhi's apartment and go to the first room on the top floor then go down the long, dark hall and type 5698 in the pad.

Unlock National Guard Costume:
In the Manhattan Streets level go to the open area before the penthouse and climb the pipe. Then jump left and go down to the next platform and look in the corner.

Unlock Shadownet Agent Costume:
In Kokubo Sosho go down the elevator where lasers are at the bottom and find a ladder to climb back up. The room will have lasers and the costume.

Unlock Snow Guard Costume:
In Battery Level get the wrench, and go to the U shaped room and enter the keycard room. Take out the guard and climb on the crate and smash open the crate next to it.

Unlock Thermal Suit Costume:
In Hokkaido Level find the wrench and then search for the man who is shooting on the roof. When you get him fall through the vent and exit the room smashing the door.

Unlock Camouflage Sam Costume:
In the Lighthouse level snipe the man on the roof but don't rappel down. On the high right corner is the costume.

Unlock Argus Mercenary Costume:
In Machi Akko go to the bar and use the microphone and look behind you for a keycard then go back to the hallway with three doors and use it on the closet.

Unlock Displace Mercenary Costume:
In Display Level go to floor 3. Use the optic cable to see which room has the green package. Enter the room, and use keypad code 5800

Unlock Short sleeved Sam Costume:
In Bank Level go to the small vault left of the computer and use the lockpick