MAP10: Refueling Base (Doom II)

MAP10: Refueling Base (MAP40 in PSX/Saturn) is the tenth map of Doom II. It was originally started as a Doom map by Tom Hall (and did appear as E1M6 of Doom 0.5), but did not make it into the game and was instead completed by Sandy Petersen for Doom II. It uses the music track "The Demon's Dead". This map is notorious for having a massive monster count, which is specially high on Ultra-Violence and harder difficulties where they near 300 monsters.

Walkthrough
Right at the start of the level, open the blue-triangled wall ahead and to the right (A). Inside is a shotgun and some ammo. Continue down the stairs and relatively straight through the opening in the stone wall. You can lower the vine-covered column here to reveal a chaingun and stimpacks as well as a few spectres. Continue through this room and out the opening leading outside. Go through the tan door to the left. The next room is dark and contains several silver alcoves and holds dozens of zombies (B) (utilizing monster infighting and weapons with splash damage will help you survive this room). One of the alcoves in the southeastern end of this room contains a yellow key (C). Pick it up and return outside.

Make your way to the opposite end of the long outdoor area and open the door there. The next room is very large and dark, and is home to several imps, revenants, and arachnotrons. Go through either of the tunnels at the north end of this room and you'll reach a stairway leading into a brightly lit alcove in the wall. Climb the stairs and the wall in front of you will open, revealing a blue keycard (D). Pick it up and return outside once more. If the wall containing the blue key closes, you can open it manually.

Once back outside, enter the round central room via the passage in the wall at about the midpoint of the outdoor area (E). Continue through the door to the south into another dark room. Clear the area of enemies, then head through the yellow door in the southwest corner (F). Proceed through another short room and through the blue door (G). Continue through one last hallway, through the exit door, and flip the end switch. In the last two rooms be aware of the Cyberdemon on the other side of a barred window (H).

Official

 * 1) In the northeast corner of the map is a large chamber with several silver alcoves in the walls. The back wall of most of these alcoves has four small UAC logo panels. However, others have a single large UAC logo. The first of such is located on the north wall of alcoves, near the northeast corner of the room. Shoot the back wall to open a secret area behind it, containing a soul sphere (I).
 * 2) The same as secret #1, but located in the alcove on the east side of the westernmost column in the center of the room. Behind the wall are some light amplification goggles and a combat armor vest (J).
 * 3) The same as secrets #1 and #2, located in the alcove on the western wall of the southernmost column in the center of the room. Behind the wall is a single bulk cell (K).
 * 4) Across from and a bit south of secret #3 is another alcove with a shootable back wall with a berserk pack behind it (L).
 * 5) An alcove in the southeast corner of the same room as secrets #1-4 contains a switch. Flip it to open a secret shortcut to another area of this level (M).
 * 6) Directly across from the alcove the yellow key is found in is yet another alcove with a shootable back wall. The passage behind it leads to a wall with baron of hell faces on it (N).
 * 7) Open the wall mentioned in secret #6 and step through to be teleported to yet another secret area, this time allowing access to the Cyberdemon room below. Before exiting this area, pick up the invulnerability sphere and box of bullets to your left and right, respectively (O).
 * 8) Near the center of the level is a large circular area with four ovoid "fuel tanks" in its center. Enter this room through the passage on the east side to open the fuel tank on the west side of the room (P).
 * 9) The same as secret #8, but enter from the western passage to open the eastern fuel tank (Q).
 * 10) The same as secret #9, but enter from the south passage to open both center fuel tanks. Both are counted as separate secrets (R).
 * 11) See secret #10.
 * 12) From the "fuel tank" room mentioned above, go through the western exit and follow the fork in the path to the right. You'll be taken to a room with a pair of nukage pools. On one of the wall near the entrance to this room is a wall with a brown upside-down triangle on it. Simply pass close to this triangle to open a secret passage in the nukage pool on the left. At the end is a series of three platforms leading up to a megasphere, each of which counts as a secret (S).
 * 13) See secret #12.
 * 14) See secret #12.
 * 15) There is a large dark room in the eastern side of the level which has a single blue light on the ceiling. In the southeast corner of this room is a wall that lacks the yellow lights on the walls surrounding it. Open it to reveal a secret passage leading to another room (T).
 * 16) After passing through the shortcut in secret #15 and arriving in the new room, follow the wall on your right until you come to a pair of green columns. Open the wall between these columns (U) to reveal yet another secret area.
 * 17) From secret #16, continue west in this room until you reach a UAC door in the northwest corner. Go through the door and pick up the rocket launcher to the right. From the platform the rocket launcher was on, run onto the platform straight ahead of you holding the security armor (V).
 * 18) In the same room as secret #17, but on the opposite side, is a raised alcove with a pair of rocket boxes in it. Simply use the wall below this alcove as you would a lift to lower the rocket boxes (W).

Non-official

 * 1) The wall with blue triangles on it in front of you at the start of the level can be opened to reveal a secret passage leading to a shotgun and some health bonuses (X). This is also a good place to take cover from large swarms of enemies when ammo reserves are low as they can only enter one at a time.
 * 2) From the starting point of the level, there is a white hall southeast from you, which is bordered at its south side by the big room containing 4 "fuel tanks" and at the east side by a darkened room; in this room, the big white pillar covered in vines can be lowered like a lift. It houses Spectres, Stimpacks and a Chaingun.
 * 3) To get the seemingly unreachable soul sphere in the south end of the level, press the back wall of the northern alcove (Y; just across from the switch that lowers the lift next to you). Or, just go backwards into the alcove opposite the switch, run into the switch and press it, and run to get the items.

Bugs

 * 1) The southmost blue key door leading to the Cyberdemon is type 32 (P1; Open and Stay Open), but the back is type 1 (PR; Open, Wait, Then Close). This means you can be locked out of the room by triggering the back of the door (unless you find the secret teleporter in the northeastern area).
 * 2) On higher difficulty settings the barracks area is loaded with zombie soldiers, which can lead to game crashes on the Sony PlayStation version.

Trivia

 * MAP10: Refueling Base is perhaps the oldest map that was nominated for use in DOOM II; it originally appeared in Doom v0.5, an early Alpha version of Doom, released in May 1993.
 * The music for "The Demon's Dead" is inspired by the track "After All (The Dead)" by Black Sabbath.

Records
The Compet-N records for the map are:

Things
es:MAP10: Refueling Base (Doom II)