Getting to the Blue Key Slot (8)

You'll start in the Control Room area. Head to the end of the hallway where you'll see the Blue Key slot. Pop your Blue Key in there, and bam! A section of the wall slides open, revealing an elevator with a Trooper chilling inside. Hop in and take it up.

You'll pop out into a dark room. This is where the big computer is. Watch out, there are a few Troopers in here, but you'll also find some Body Armor and a Large Medikit to help you out.

After dealing with the enemies, you'll need to navigate the Gamma Transport section. If you happen to fall off the bridge here, don't sweat it – a couple of Enforcers will be waiting below. You can use a nearby box to jump back onto the building and find a Large Medikit. The bridge itself will lead you to the other side of the building where a Chaingun Cannon is waiting. Down on the ground, you'll spot some Shrink Ray Ammo. Follow either side of the bridge, and you'll end up in the same spot where an Enforcer is ready for a fight.

Keep an eye out for SECRET 4. Where the two paths merge, there's a computer panel on the wall you can interact with. Inside, you'll find a Shrink Ray and two Laser Tripbombs – super useful stuff!

Next up is the Gamma Transport Corridor. Take the transport cart to the other side. Be ready for a couple of Enforcers. There's a compartment with a Portable Medikit, and at the far end of the room, you'll find some Devastator Ammo.

Head through the doorway and take the elevator down. You'll see some Pistol Ammo on either side of the elevator. Before you go too far into the next area, you might want to rig the hallway with some Pipebombs. Seriously, do it! The walls are about to explode, and four Enforcers will come charging out. In the holes left by the explosion, you'll find some Freezer Ammo and a box of Shotgun Shells.

Go through the next door into the Sewage Pool area. You'll find two Small Medikits right beside you. Get ready, because you're about to be attacked by a bunch of enemies, including Sentry Drones, Octabrains, and Enforcers at the far end of the pool. To cross, find and press the switch. Platforms will rise from the bottom of the pool, creating a bridge. On the other side, you'll find some Shotgun Shells and a Large Medikit. Head into the door, go up the stairway, and open the next door to continue.