In Dead Rising 2: Off The Record for the PC, PS3, and Xbox 360, the Protoman Costume is similar to the Megaman costume from Dead Rising, but with a strong attack that shoots three blasts.
To unlock the Protoman Armor, you need to unlock The Challenge Experience achievement / trophy by getting a bronze on all single player challenges.
Check out my other guide if you’re looking for the rest of the Protoman Costume pieces.
