Getting the Blue Key / Getting to the Blue Key Slot (11)

Enter the Operating Room and proceed to the Teleport Pad.

You will arrive in the Outer Waterfall Room, starting near four Large Medikits. You can go left or right.

Regardless of the path, you will fight a Trooper at a shaft entrance, and an Alien Drone and an Enforcer inside the shaft.

The shaft leads to the other side of the area, with Chaingun Cannons at either entrance.

On the upper portions above the shaft, use the Jetpack (a device that allows temporary flight) to reach elevated platforms. On the right path, find two boxes of Shotgun Shells (SECRET 1). On the left path, find two Chaingun Cannon Ammo (SECRET 3).

On the right path, use the Jetpack to reach elevated platforms and find two Devastator Ammo (SECRET 2). On the left path, use the Jetpack to reach elevated platforms and find two RPG Ammo (SECRET 4).

Enter the two Green rooms, fighting an Enforcer and a Trooper in each.

Go up the ramp in the middle of the room to the Code Room.

Fight the Trooper at the top of the ramp. Inside the room, fight two Enforcers and a Trooper.

Collect two Pipebombs, four Devastator Ammo, and two Large Medikits.

Hit the switches on the column in the order X O X to open a door opposite you, down the ramp.

Enter Outer Shell 1. Use the Chaingun Cannon immediately due to the number of Troopers.

Circle the area left or right. Going right involves fighting Slimer Eggs and Captains. Going left leads to the next area faster.

This area has Slimer Eggs, guarded by two Enforcers. An Alien Drone and an Octabrain are in a nearby hallway.

Amidst the eggs, find an RPG and two Large Medikits. In the corners are two Devastator Ammo, and behind the big column are two RPG Ammo.

In a small area opposite the big column, find a Devastator and Scuba Gear.

On the big column, jump into a specific opening to find Pipebombs, two Devastator Ammo, RPG Ammo, Chaingun Cannon Ammo, and two Small Medikits (SECRET 5). This pipe leads to the Inner Shell area.

Alternatively, reach the Inner Shell area via the water. Be cautious of Alien Drones and Octabrains underwater.

Destroy Slimer Egg clusters around columns to destroy the columns.

In the center of the underwater area, emerge into the Inner Shell area. Fight three Enforcers and three Troopers.

On a ledge, find Body Armor. A door opens beside you when you reach this ledge, revealing a pool.

Fight an Enforcer and an Alien Drone in the pool room. Swim down into the small room beneath it.

Inside this room, find Shotgun Shells and Chaingun Cannon Ammo. Hit the switch to open a viewing wall.

Touch the second switch to the right of the first to open an underwater door.

Enter the Blue Key Room, which has two crushing doors.

Find switches to the left and right of both pistons. Hit all switches to open a compartment.

In the compartment, collect the Blue Key, Atomic Health, and Body Armor.

Return to the Inner Shell area and go back to the ledge with the pool.

Proceed to a higher ledge; a door will automatically open.

Fight a Battlelord and an Enforcer. Collect two Devastator Ammo found here.

Use the Blue Key slot in this area. Enter the resulting room.

Find a Portable Medikit and a switch that raises green columns in the Purple Acid area.

Return to the Code Room area.