Map 10: Refueling Base

Immediately upon starting, open the wall with the blue symbol to find a Shotgun and ammo.

Enter the room to the left, clear out Imps and Hit-Scan enemies. Use the Super Shotgun on the Pain Elemental and then deal with the Lost Souls. Collect minor pickups. The "Ivy Column" can be LOWERED to reveal Specters, health, and a Chaingun.

Return to the previous area and head south. Clear out Imps and Hit-Scan enemies in the open room and gather items in the lower area.

Stand by the oval pods to the south and clear any remaining minor enemies.

Be aware of FOUR TRAPS in this area, each associated with the oval pods. These count as Secrets 1–4/18.

Approaching the southern door triggers the two middle pods, containing Imps and Hit-Scan enemies. The southern pod contains a Radiation Suit.

To open the east and west pods, walk to the edge of the opposite hallway. Each pod contains two Pain Elementals; use the BFG or other powerful weapons. These pods also contain items.

Head back to the Ivy Column room and enter the hallway beyond. Beware of enemies, including a Revenant, potentially exiting the north door.

Enter the north room. Move slowly through the cubby-areas, using the chaingun to clear out numerous hit-scan enemies. Find the Yellow Key Card and several secrets.

Secret 5/18: In the southwest corner, interact with a cubby with a "UAC" logo to find ammo and a Berserker Pack.

Across from where you found the Key Card, a switch opens a pathway south (leading to Arachnatrons, which can be skipped for now). This is Secret 6/18.

Secret 7/18: On the northern wall, a "UAC" logo leads to a Supercharge.

Secret 8/18: On the northwest island in the center area, a "UAC" door reveals a Mega Armor and Light Goggles.

Secret 9/18: On the southeastern island in the center area, a "UAC" door contains cell ammo.

Head to the eastern wall for Secret 10/18. Inside, defeat Pinky Demons (punch or chainsaw to save ammo) to get a Backpack.

Open the demonic wall to teleport to another area for Secret 11/18.

You will encounter a Cyberdemon. Quickly save your game. Grab the Invulnerability Orb to your left, along with nearby bullets. Use cell ammo for BFG shots to defeat the Cyberdemon. Gather the remaining cell ammo and note the SECOND Invulnerability Orb.