Digital camera
Successfully complete the game. The digital camera will be available when a new game is started. Also, the digital camera is locate in Strut E Shell 1. Go to the bottom of the screen and locate the platform with three red lights on it. Climb up onto it and equip the Z.O.E. Box. When the conveyor stops, press [Action] to climb on. You will be taken to another room. Press [Action] again to get off and retrieve the Digital Camera. Exit the room in the same fashion.

Stealth, Bandanna and Wig bonuses
Complete the following goals to get the Stealth (invisibility), Bandanna (infinite ammo for Snake), and the Wig (infinite ammunition for Raiden). To get Stealth and Bandanna, complete the Tanker mission three times on three different difficulty settings (all on the same saved file) and get all the dog tags. To get Stealth and Wig, complete the plant three times on three different difficulty settings (all on the same save file) and get all the dog tags.

Sunglasses
Successfully complete the game two times and Snake and Raiden will be wearing sunglasses.

European Extreme difficulty
Successfully complete the game on the normal difficulty setting to unlock the European Extreme difficulty setting.

Boss Survival mode
Successfully complete Sons Of Liberty, all VR missions, all alternative missions, and the Snake Tales missions to unlock Boss Survival mode.

Photograph mode
Successfully complete bomb disposal mode, hold up mode (alternative missions), and eliminate mode to unlock photograph mode in the VR Missions.

Casting Theater option
Successfully complete Sons Of Liberty on any difficulty setting to unlock the "Casting Theater" option.

Play as Ninja Raiden
Successfully complete 50% of the VR missions with Raiden to unlock Ninja Raiden in the VR Missions.

Play as Raiden X
Successfully complete 100% of the VR missions with Raiden and Ninja Raiden to unlock Raiden X in the VR Missions.

Play as Pliskin
Successfully complete 50% of the VR missions with Snake to unlock Pliskin in the VR Missions.

Play as Tuxedo Snake
Successfully complete 100% of the VR missions with Pliskin to unlock Tuxedo Snake in the VR Missions.

Play as Metal Gear Solid 1 Snake
Successfully complete 100% of the VR missions with Snake, Pliskin, Tuxedo Snake, Raiden, Ninja Raiden, and Raiden X to unlock Metal Gear Solid 1 Snake in the VR Missions.

Alternate ending sequence
Successfully complete a Snake Tale to unlock the M9. Begin a game and use M9 to stun the Bosses instead of killing them to view an alternate ending sequence.

Radio shots
To knock out an enemy's radio easily, when you hold them up shoot it (on the belt to the right of their back). Also shoot an enemy's radio when they are knocked out to prevent them from calling for help if they wake up.