Getting the Red Key / Getting to the Red Key Slot (4)

You'll start on a catwalk. Take out the two Alien Drones at the far end. You can also snipe Slimer Eggs and an Alien Drone below, and deal with three Troopers on Jetpacks. Descend the elevator to find two Devastator Ammo. The Yellow Key door is here, while the Red Key door is at the catwalk's end. Return to the catwalk entrance and go up the stairs.

Proceed down the Mounted Gun Hallway. Shoot the fire extinguisher near the two Mounted Guns to destroy them, then grab the Pistol Ammo. At the end of the hallway, walls will open, revealing four Mounted Guns on each side. Some may destroy each other, but eliminate the rest. You now have three path options: left (Mess Hall), right (Crew's Quarters), and center (Captain's Quarters, containing the Red Key).

Mess Hall (Left Door): Enter the Mess Hall to face a Commander behind the counter, three Captains, and two Troopers. Find RPG Ammo behind a column, a Large Medikit on a window sill, and Shotgun Shells in a trash can.

SECRET 2: Behind the window, on a counter with a knife, is a switch. Activating it opens a compartment with a Portable Medikit.

Crew Quarters (Right Door): Enter the Crew's Quarters and defeat the visible Captain and an approaching Alien Drone. More Troopers will appear. The left room contains six Troopers and an Alien Drone, suitable for Pipebombs or the Chaingun Cannon. Find a Large Medikit on the couch and a Chaingun Cannon behind the TV.

SECRET 3: Jump on the TV to open a compartment across from it containing a Shotgun. You'll get the secret credit just by jumping on the TV.

Sleeping Quarters: Opposite the previous room are Sleeping Quarters with many beds. Fight a Trooper immediately, then a Trooper and a Captain near the right set of beds. In the right beds, find three Chaingun Cannon Ammo in a metal chest, plus Pistol Ammo and a Large Medikit on the beds. In the other sleeping quarters, an Alien Drone and a Trooper are present. On the beds, you'll find Steroids, Freezer Ammo, and a Large Medikit.

Captain's Quarters (Center Doors): This area is dangerous, housing three Alien Drones and a Commander. After defeating them, likely with Pipebombs, collect the Red Key from the desk. Other items include Body Armor and a Large Medikit near the bed, Shotgun Shells near the drink counter, and Night Vision Goggles and Shotgun Shells on the desk. Return to the Catwalk area to use the Red Key door.

SECRET 4: Above the desk in the Captain's Quarters is a clock. Interacting with the clock lowers a bookshelf, revealing a Shrink Ray, two Microwave Expander Ammo, and two Atomic Health.