Map 5: The Waste Tunnels

Begin by picking up the Super Shotgun and Supercharge, but be cautious of the Chaingunners and soldiers in the next room. Clear them out before collecting the Supercharge.

Head south of the Supercharge to find an elevator leading down. Before descending, clear out the two elevator traps along the north wall, which contain Imps, health, and ammo.

Take the south elevator (south of the Supercharge). Prepare for numerous Imps, some of which may be on the elevator itself.

After clearing the Imps, proceed south of the elevator to an area with windows where you can eliminate hit-scan enemies. You will find a Red Door and a Blue Door here.

On the east side of the outdoor area, run through the windows to reach a ledge. A wall will open, revealing three gunners; eliminate them. To the right, you'll find a Chaingunner and an Imp near the Blue Key.

To find SECRET 1/3, enter the area where you found the gunners. On your left, open a wall and proceed straight to a gap in the wall. You will be lowered into a room containing a hit-scan enemy and a Plasma Gun.

After exiting the secret area, kill the Imps past the caged window and hit the Skull Switch to leave the room.

Instead of taking the eastern elevator, return to where you were lowered down and go through the northern door.

In this small hallway, a Specter will emerge from a trap behind you as you turn right. Eliminate it and continue.

Around the next bend, a wall will open, revealing a Chaingunner. Be prepared to face him.

Near the next turn, across from where you found the Plasma Gun, is another Supercharge. Interacting with the small wall behind it reveals SECRET 2/3: a Berserk Pack.

Return to the dark area where you killed the Imps and proceed Southeast. A door will slam shut behind you, trapping you.

Open the first three doors on your right to kill Imps. The fourth door on your right is not yet accessible.

Open the first door on your left, kill the Imp, and hit the switch to open the door that trapped you.

Open the next door on your left, kill the Imp, and note that its switch opens a door to the east, revealing three Shotgunners. Eliminate them upon exiting.

Where the Shotgunners were, you will find a Mega Armor and a box of bullets.

Open the last door on your left, kill the Imp, and hit its switch. This opens a door across from you, leading to a southern hallway.

In this hallway, kill the hit-scan enemies behind bars.

In the water to the left, kill Imps and a Pinky. The water to the right leads to a door where some hit-scan enemies were previously located.

Explore the Imp Room in the water to the right and then left to find a Rocket Launcher.

Clear the remaining water area, eliminating Lost Souls and Imps. You will find stairs leading to an upper room.

In the upper room, use your chaingun to defeat the Hit-Scan enemies. To your right is a door leading behind bars, which you will need to access for ammo.

Take the door to the right to find a small room with water containing Imps and the Red Key Card.

With the Red Key Card, proceed down the waterway, killing Lost Souls. Drop down to the previous waterway to access the red door.

Upon entering the red door, watch your right for an Imp, then head up the stairs to claim the Blue Key Card.

Proceed towards the exit, past a second Red Door, to the Blue Door.

Enter the Blue Door. You will find the Yellow Key Card. Picking it up triggers the appearance of three Cacodemons from across the water.