REX Hangar & The PAL Key

Unlocking the heavy armored blast door with the Level 7 Keycard brings you into the Metal Gear REX Test Hangar:

• Gun Cameras: Lob Chaff Grenades to blind the automated surveillance gun turrets covering the upper catwalks.
• Stinger Missile Cache: Along the right-hand catwalk, recover 15 Stinger Missiles, critical for the impending final battles.

Climb the gantry stairs to the upper platform overlooking REX's head. Use your Binoculars to overhear Liquid Snake and Revolver Ocelot inside the control room plotting world military domination.

Attempting to enter the control room prompts Ocelot to fire a precision shot, knocking the PAL Key out of Snake's hands and down into the drainage sump below:

• Sprint down the gantry ladders to the ground-floor pool.
• Equip Thermal Goggles to locate the shimmering yellow signature of the key submerged in the wastewater.
• Beware of aquatic proximity mines and deceptive decoy items.
• Retrieve the PAL Key and return to the upper control room.

The PAL Key is composed of a shape-memory alloy that alters its physical card layout according to temperature. You must input the key into all three terminals:

1. Terminal 1 (Room Temperature / Yellow): Insert the PAL Key directly into the center terminal (yellow slot).
2. Terminal 2 (Sub-Zero Cold / Blue): Backtrack to the frozen warehouse where you fought Vulcan Raven. Equip the PAL Key in your active inventory and stand in the snow until its card icon turns Blue. Run back to the control room and insert it into the left terminal (blue slot).
3. Terminal 3 (Extreme Heat / Red): Backtrack to the Blast Furnace boiler room. Stand beside the molten metal vats until the card heats up and turns Red. Sprint back at maximum speed: lingering in cold sectors will normalize the card back to room temperature. Insert it into the right terminal (red slot).

Inserting the third key triggers a chilling automated broadcast: "Nuclear launch override confirmed. Metal Gear REX armed and ready!".

• The Codec chimes: Master Miller reveals the real Miller was murdered days ago in his home... you have been speaking with Liquid Snake in disguise all along. Snake was tricked into activating REX.

• Blast doors slam shut, locking Snake inside as lethal nerve gas floods the chamber.

• Equip the Gas Mask immediately to slow vitality drain.

• Radio Otacon (141.12) urgently on the Codec to hack the facility controls and override the emergency security door.

  Rapid Evacuation

  The instant Otacon cracks the door lock, dash out into the main hangar to confront Liquid Snake face to face.