Complete the game once and the 'First-Person View' mode will become available in the 'Special' option. To switch between 'First-Person View' mode and 'Normal' mode tap Triangle twice rapidly. Your rank during your first play doesn't affect anything.
Unlock First Person Play Mode: On any difficulty complete the game once (except for the 'Very Easy' setting). An option for first person play mode will then be unlocked on the 'Special' option at the Main menu. Then during gameplay quickly press Triangle(2) after the option has been selected to switch the view to first person.
Unlock Infinite Ammo: Complete the game without submitting to Ocelot when being tortured to save Meryl and then at the end of the game you will receive a Bandana. Save your game and start a new game using the 'Saved' game. When you now equip the Bandana you will be able to use an unlimited amount of ammo and will not have to reload your gun.
If you submit in the torture room with ocelot, meryl will die in the ending and you will escape with otacon.in the ending, otacon will give you his stealth camo. Listen Carefully! Watch the credit's and ending, i know it's boring. at the end, it will give you the options of saving. Save over your data (to save space on your memory card). If you endure the torture twice, then otacon will stay in the building and meryl and snake will have a little love ending. Meryl will find a bandana outside and it say's limitless on it. Then follow the directions above.when you have it and a weapon equiped it will give you unlimited ammo