Unlock the following characters by entering the corresponding passwords:
CHARACTER - PASSWORD Cunningham - "JUNKER" Elisa - "THE-L" Eva - "E.APPLE" Ga Ko - "!TRAUMER" Gene - "ERBE" Major Zero - "1+2-3" Null - "Hunter-n" Ocelot - "R.R.R." Para-Medic - "PM-EMS" Python - "LQ.N2" Raikov - "IVN =RV" Sigint - "DARPA-1" Sokolov - "SATURNV" Teliko - "T.F-ACID" Ursula - "PK +ESP" Venus - "MGA2VE"
To unlock Cunningham alternatively, defeat Cunningham on any difficulty setting by stamina depletion with the MK22 and complete the game before the in-game date reaches January 1, 1971. Save after the credits and load the game. Get to a point where you can save the game. Save it, then exit the game completely. Restart the PSP, load your game, and you will get a message saying you have a new solider, which is Cunningham.