Unlock Lieutnant Cunningham:
On any difficulty defeat Cunningham by 'Stamina Kill' and beat the game before January 1st 1971. Cunningham will then be unlocked when you make a new game.
Defeat Null twice by either 'Stamina kill' or 'HP kill' and then beat the game. Null will then be unlocked when you make a new game.
Unlock Para Medic:
On the Comm Tower stage contact her on the radio then later in the Hospital stage rescue her. Place spies in the Hospital.
Place spies in Western Wilderness then clear the Guard House mission. You will then get a report of a prisoner being held there.
When Snake has been captured and rescued you can contact Sigint on the radio at the Comm stage then rescue him in the town.
Unlock Major Zero:
Have a Metal Gear Solid :DGN game save on your PSP's Memory Stick (Second Playthrough only).
Have a MGA game save on your PSP's Memory Stick. (Second Playthrough only)
Have a MGA 2 game save on your PSP's Memory Stick. (Second Playthrough only)
In one playthrough recruit 200 soldiers and 'Stamina' kill Gene.
Give the Saturn V blueprints to Sokolov
Kill Python by 'Stamina kill'.
Get a Medic level of 80.
Added by: Sanzano Dec 15th 2006, ID#1011