Secrets for TNT:Evilution (Final DOOM)

list by Chris Call


Go straight to the level you want--click the level number here
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MAP01Secret sector numbers: 52
System Control

On the east side of the map is a courtyard that is overlooked by a small tower. That courtyard (52) is a secret sector. To get there, go down the steps from the small tower. To the north of that room is a door; just beyond that door on the east is a hidden door leading to the courtyard.

MAP02Secret sector numbers: 66, 114, 126, 153
Human BBQ

In the large outdoor courtyard is a small square structure containing a soul sphere (66). It is a secret area.

In the southwest corner of the large indoor courtyard is a secret room (114) accessible from the ledge.

To the north of the stairs in the indoor courtyard is a ledge leading to a small platform. To the south of the platform is a door to a secret room (126).

In the SW of the open courtyard is a ledge that can be accessed by jumping off of the walkway on the west side. To the south of that ledge is a hidden door to a secret sector (153) containing an armor helmet.

--- Useful information about this level:

To get onto the stairs in the indoor courtyard, run and jump off of the raised area to their west.

In the room with all of the barons and knights on pillars, there are several teleporters. Most of them teleport you on top of one of the bad guys, killing him instantly. The SE switch lowers one of the pillars, releasing a baron.

MAP03Secret sector numbers: 228, 230, 278
Power Control

There is a secret room (230) to the south of the teleporter in the southwest corner of the system of stairs and corridors that surrounds the central courtyard. Teleport to the room in the center of the courtyard and then back. Push on the south wall while still on the teleport pad.

In the SW corner of the room due north of the central courtyard is a secret area (278) containing a rocket launcher and shells.

In one of the west rooms is a teleporter that teleports to the east room. The teleporter in the east room returns you to the teleport pad (228) in the west room, at which point you get credit for a secret.

MAP04Secret sector numbers: 64, 122, 129, 133, 164, 165, 168, 335
Wormhole

(Four secrets:) North of the starting room is a long corridor. Two candles in the corridor mark the location of hidden doors. The sectors beyond each door (164, 168) are secret. The hallway in the "mirror image" part of the map also has two similar hidden doors to secret areas (129, 133).

The area to the east of the lift in the hallway north of the starting room contains a corner to the NE that teleports you into the mirror image section of the map. That corner (165) is a secret area.

In the NE corner of the triangular system of passages north of the starting room is a hidden door leading to a system of caves full of hellspawn. The secret sector (335) is just beyond the hidden door.

MAP05Secret sector numbers: 91, 106, 169
Hanger

There are three secrets near the same general area of the map: The small room at the bottom of the stairs on the north side of the large room that overlooks the courtyard. Using that room as a reference:

The stairs north of that room lead to a room with a hidden door to a secret area (169) containing a backpack.

The stairs leading south from that room go right past a hidden door (on the east side of the stairs); behind it is an area (91) with armor and shells. Across the stairs from that door is a room with a hidden door leading to an area (106) with a chaingun and a stimpack.

--- Useful information about this level:

In the room with five round platforms, pressing on the pointed platforms to the north and south will lower the platforms, except for the center platform. Pressing the center platform lowers the pointed platform to the west. Getting onto or off of that platform should lower the center platform.

To the east of the room with the five round platforms is a passageway with a hidden area to the north. On the west side of that hidden area is a switch that lowers one of the stairs in the room with the circular staircase. Beyond the lowered stair is a computer map.

MAP06Secret sector numbers: 98
Open Season

On the ledge to the east of the room with the two crushers (in the NE corner of the map) there is a hidden door to the east leading to an area (98) containing a backpack and a soul sphere.

MAP07Secret sector numbers: 51, 115, 142, 151
Prison

In the room with the double staircase just beyond the starting hallway, there is a small secret room (142) to the north of the west staircase.

On top of the fortress west of the moat, there is a small room containing a lift (151) that is activated by walking along the terrace surrounding that room. Secret credit is given for getting onto the lift.

There is a small square tower along the south edge of the moat. On the south side of the tower is a switch that lowers lifts on both the north and south sides of the tower. The north lift (51) is a secret area.

The one secret that seems to give people problems is near the exit. Stand on the ledge just outside the exit door and turn around. One of the pillars is marked with lights. If you press on the lighted side of the pillar, it will open a door at the end of the long walkway between the two lava lakes, revealing a circular area (115) containing a soul sphere and also releasing some monsters.

MAP08Secret sector numbers: 115, 121, 145, 305
Metal

Just behind (to the south of) the starting area is a secret area (305) containing a chainsaw. Press the wall to the west of the starting area to open the door.

There is a large room in the center of the map containing imps in cages. In the SE of that room is an alcove. To the east of the alcove is a hidden door to a secret area (115) with a switch that lowers the platform in the large room.

North of the large room is another big room with some pillars. To the SW of that room is a small hallway. Shoot or press at the west end of the hallway to lower a lift to a secret area (121) containing a soul sphere and a rocket launcher.

To the east of the room with the pillars is a hidden door to a secret area (145).

MAP09Secret sector numbers: 138, 172, 219, 238, 251, 252, 253, 269, 383, 401, 404
Stronghold

Shortly after the starting area is a more or less C-shaped curved hallway with a window through which you can see sergeants, but they can't see you:

At the south end of the C-shaped hallway is a room with a long stairway to the south. The sector at the top of the stairs (383) is secret.

To the east of that room is a large room with boxes in it. Crossing an invisible line just north of the first box you come to opens a door to the south of the window in the C-shaped hallway. Through that door, up the stairs, and to the right is a hidden lift that takes you to an area (138) with some goodies.

South of a different room full of boxes is a hallway in which many doors open on either side to reveal chaingunners. To the south of one of the revealed chambers is a hallway with three secret sectors (401, 402, 403).

There is a room in the NE with a slime pool and two stairways out of the slime:

In the SE of that room, behind the health potion, is a lift (251) leading to an area (252) with some goodies.

East of that room is a circular room. East of there is an area (269) with mega-armor and rockets. A teleporter there takes you to a room with an L-shaped console.

The floor of the room itself (219) and the L-shaped floor containing goodies (253) are both secrets. The east teleporter in that room leads to a secret hallway (238) off of the starting area.

At the bottom of the stairs to the west of area with the exit is a hidden door on the south wall leading to a secret area (172) with some health.

MAP10Secret sector numbers: 56, 57, 58, 59, 61
Redemption

All five secret sectors are part of the same hallway. South of the starting courtyard is a room with an exit to a lift on its west side. On the south side of the lift is a hidden door leading to the hallway with the secret sectors (56, 57, 58, 59, 61). Some of the sectors are rather small and you may not get credit for them if you walk over them too quickly.

MAP11Secret sector numbers: 153, 154
Storage Facility

There are three passageways leading from the middle room to the west room. On the south side of the middle passageway is a hidden door to an oval room. The floor under the door (153) is the secret sector.

On the south side of the oval room is a lift that takes you to the southernmost passage from the middle room to the west room. That lift (154) is a secret sector.

--- Useful information about this level:

On the south side of the southernmost passage from the middle room to the west room is a door that is activated by walking across the middle of the oval room described above. There doesn't seem to be enough time to walk over the line and get up the lift and across the passage before the door closes again; however, you can run into the oval room and back out again, then run east and south up the crates and enter the southernmost passage from the middle room in time to catch the door while its open. There is an oval room beyond the door containing a megasphere.

To get the Megasphere which is outside and just south of the Storage Facility, on top of a crate (this often doesn't work) try letting the Arch-vile pop you up there. Gotta be healthy to begin with, but since you get a megasphere, it's worth it. Stand on the inside corner of the L-shaped box, so that the archvile blast will knock you up and over the megasphere.

MAP12Secret sector numbers: 213, 214
Crater

East of the red key door is a large rectangular room. A hallway leads east from that room to a lift. East of the lift is a room with arachnotrons on a platform, but instead of entering that room you can also ride up the lift. To the north of the lift is a secret sector (213) containing a berserk pack. To the south is another secret sector (214) that is the start of a long passageway.

MAP13Secret sector numbers: 92, 161, 201, 210, 215, 233
Nukage Processing

To the north of the starting room is a hidden door to a secret area containing a backpack, a shotgun, and a double barreled shotgun.

On the east side of the room to the east of the starting room is a lift that can be lowered to give access to the courtyard beyond. The lift is a secret area.

A staircase leads up from the large room west of the courtyard to an area with computer equipment on either side, and then to some more stairs. In the east section of computer equipment is a hidden door to a secret area with armor and shells.

North of the area described above is a room with a lift in its NE corner. On the west side of that room is a hidden door leading to a secret area with a medikit, shells, plasma gun, and cells.

--- Useful information about this level:

In the room with the six large pillars in the north part of the map, there is a hidden door on the west side of the middle pillar to the west. Inside are some goodies.

On the east ledge around the large courtyard is a teleporter to an area with a lift that leads to an invulnerability artifact, which comes in quite useful when fighting the cyberdemon.

MAP14Secret sector numbers: 58, 89, 223, 276
Steel Works

In the room with the four large vats of slime (molten steel?), the NW vat leads to a hallway that goes back to the starting area. One of the sectors in that hallway (58) is secret.

The raised platform (89) in the NW of the room east of the starting area is secret.

There is a secret room (223) to the SW of the room with the vats of steel. Shoot the wall at the back of the SW vat to reveal it.

There is a secret area (276) to the east of the curved hallway beyond the dark room with all the pillars and lost souls. To access it, first shoot the back of the SE vat of steel, then press the switch that is revealed in the SE corner, next to the vat.

--- Useful information about this level:

The S-shaped hallway connecting the two almost identical room contains two triggers that lower lifts in those rooms. The trigger line for the lift in a given room is at the end of the hallway that is furthest from that room. About the only way to get onto the lift is to open the door to the room, run backwards down the hallway until you hit the trigger, then dash forwards down the hall and through the door to the lift. It's very difficult to get onto.

MAP15Secret sector numbers: 172, 176, 223, 240, 292, 305
Dead Zone

A little bit NE of the starting location is a lift leading to a platform from which a stairway leads into the building. From the room at the top of the stairs, a ledge leads SW to a hallway that leads back to the NE (to a room overlooking the circular area in the center of the building). A hidden door at the bend in that hallway leads to a room (223) with a berserk pack. A secret door from that room leads to a teleporter that takes you to the exit (335) to the secret level (MAP 31, Pharaoh).

Next to the stairs that lead into the room with the pool of water (and the two Barons of Hell) is a hidden door leading to a secret hallway (240). A hidden door in that hallway leads to a teleporter that takes you to a small niche on the side of the building.

There is a Y-shaped hallway going NE from the center circle of the building. To either side of the Y are doors to areas containing chaingunners. Each of those areas has a hidden door to a secret area (172, 176).

In the SW corner of the area with the diamond-shaped slime pool (to the NE of the room north of the Y-shaped hallway) is a door with a "Poison" sign that leads to a secret room (293) containing a backpack.

A teleporter in the zigzag passageway off of the Y-shaped hallway leads to a platform (305) from which you can get an invisibility artifact.

--- Useful information about this level:

The switch by the stairs to the south of the center circular room lowers the pillar on which the BFG stands.

MAP16Secret sector numbers: 25, 32, 156, 172
Deepest Reaches

The section of the hallway (25) overlooking the initial slime pool on the NE is a secret. NE of that spot is a lift. Just NE of there (on the north side of the hall) is a large secret area (172) containing rockets and a mega-armor.

To the NE of the area overlooking the initial slime pool is a small area (32) with a box of ammo.

There is a secret area (156) between the stairway that leads up from the room with the throne and the hallway that runs from the top of the stairway to a point overlooking the stairway. A hidden door in that hallway opens to reveal the secret section. Move quickly if you want to get the goodies on the ledge inside, which raises.

MAP17Secret sector numbers: 59, 115, 167, 188
Processing Area

The area (59) to the south of the starting area is secret. It is accessed through a hidden door in the E/W hallway north of the starting area.

In the open area to the north of that E/W hallway is a pillar with a soul sphere. It is lowered by a switch on the SW console in the room just east of the pillar. The top of the pillar (115) is a secret.

North of that open area is another E/W hallway. A door from that hallway to a secret hallway (167, 188) is opened by crossing a line on the south side of the central part of the small room in the north of the map.

MAP18Secret sector numbers: 125, 209, 271, 308, 342
Mill

On the east wall of the southeast corner of the hallway outside of the central starting room is a secret door leading to a ledge overlooking a large field with arachnotrons on it. The hallway is a secret area.

Along the same section of the ledge described above, there is a hidden door leading to an invulnerability artifact on a platform just outside the red key door. The first section of the passageway beyond the hidden door is a secret area.

To the northeast of the room with the four switches on a pillar in the middle is a lift that leads to a hallway overlooking the yellow key area. Along the east edge of the hallway is a hidden door leading to the soul sphere on a platform just outside the red key door. The first section of the hallway beyond the hidden door is a secret area.

Beyond the blue key door is a room to the south of which is a small walkway above a pool of slime. A switch hanging down on the east end of this room raises a platform across the slime, allowing you to press the switch at the south end. To the east of the platform is a secret area that is accessed by jumping into the slime and walking east through what looks like a solid wall, but isn't. The room beyond the false wall is a secret area. (When you attempt to leave that room, you are teleported back onto the platform.)

In the NE corner of the room beyond the yellow key door is an area that is revealed by pressing a switch at the SE corner of the room. North of that area is a hidden door to a secret area containing an invisibility artifact.

--- Useful information about this level:

In the room west of the room with the four switches around the pillar is a platform near a switch. At the other end of the room are two corners marked with lions' heads. Stand on the platform and shoot at the corners. Shooting the northeast corner will raise the platform on which you are standing, allowing you access to the switch beyond, which removes the barriers around one of the four switches around the pillar in the adjoining room. Shooting the southeast corner opens up a room to the south end of the room with the four switches.

MAP19Secret sector numbers: 35, 142, 393, 416
Shipping/Respawning

To the northeast of the room near the starting area with the six teleporters is a curved hallway. A lamp on the north side of the hallway illuminates a hidden door leading to a soul sphere. The section of hallway just beyond the hidden door is a secret area.

South of the hallway with the four blue key doors is a large oval room. To the south of that is a room with stairs in its northwest corner. That room contains a chair near a console. Just south (and a bit west) of that chair is a false wall, beyond which is a secret area containing a backpack.

On the north side of the room described above is a door to another room. To the west just beyond the door is a switch that lowers a wall at the NE corner of that room, allowing access to a teleporter. To the south of that switch is a hidden door leading to a secret area. The secret sector is the section of hallway just beyond the hidden door.

There is a platform along the south side of the area with the red key. A small step on the east side of that platform allows the player to get onto the platform after stepping off. It also lowers a lift containing some goodies. The lift is a secret area.

--- Useful information about this level:

Beyond the curved hallway described in the first secret above is a hall containing stairs leading down to a room in which is a green armor on a platform. A hidden switch on the SE part of the curve in the hallway at the top of the stairs lowers the platform, revealing a hallway to the north beyond the platform. It is virtually impossible to hit the switch and get down to the platform in time to enter the hallway beyond.

The switch in the room described above lowers a lift just outside and east of the door to the room.

You can get to some of the crates in the blue key room by jumping off of the platforms at the north and south sides of the room. Other crates can be accessed by pushing on certain crates to lower them.

Beyond the wall at the north side of the red key area is a small passageway or door of some sort. I was unable to find a way of reaching that passageway.

MAP20Secret sector numbers: 74, 186, 214, 235, 269, 270, 284
Central Processing

In the room with the boxes that is a little bit to the east of the T-shaped starting hallway, the large box to the east (74) is a secret area.

The box in the northeast corner of that room lowers to provide access to an area with a BFG 9000. The box itself (284) is a secret sector.

There are two secret sectors (186, 214) in the hallway containing an invulnerability artifact that runs northeast from the room with a lava lake around a small island.

East of the large courtyard beyond the yellow key door is another large courtyard in which there is a revenant atop a lift. At the top of that lift and to the east is a secret area (235) containing a teleporter.

A little beyond the red key door is a large circular room with a lava lake and a small room at its center. West of that circular room (and accessed through a door in the north of that room) is a series of three smaller rooms, one of which contains a teleporter. In the room to the south of the teleporter room, the east wall opens to reveal a secret area (269). In the room to the north of that room, the southeast wall opens onto another secret area (270).

--- Useful information about this level:

In the large open area to the east of the courtyard behind the yellow key door, there are several tiers of pathways around a lake. In the northeast section of the top tier is a marker near a lift that takes you to a higher level. One of the sections of the fence on that higher level (near a box of bullets) has a hole in it, allowing you to jump to the tier below and thus access the teleporter to the exit.

MAP21Secret sector numbers: 49, 246, 326, 337
Administration Center

In the SW area of the main square building is a small complex of rooms. In the NE corner of that complex of rooms is a red room containing some Hell Knights and a Cacodemon. That room (49) is a secret area. It is accessed through a hidden door on its north side, from the walkway overlooking the central pool of slime.

One of the rock shelves (246) on the island in the NE corner of the open area with the cyberdemon is a secret area.

In the area to the SW of the main square building (the room with the two crushing ceilings over the pyramid-like structure), the far east section of the south ledge (326) is a secret sector containing a BFG. At the other end of the ledge (on the north side) is a similar sector (though not officially a secret) containing a pack of cells. In order to get onto the ledge, run up the pyramid and jump across. If you miss the first time, you'll have to wait until the crushers are all raised at the same time.

In the building that stands in the center of the large open space containing the cyberdemon, there is an exit to the south. On the west edge of the exit hallway is a secret area (337) containing a mega-armor.

--- Useful information about this level:

The river on the north of the large open area leads to a spot with a soul sphere. South of that general area on the map is a spot where a section of the wall (marked by a box of shells) lowers. Behind that are an invulnerability artifact and a teleporter to the island where secret sector 246 is found.

MAP22Secret sector numbers: 94, 102, 164, 191, 193, 372, 374, 378, 379
Habitat

Directly behind (to the south of) the starting location is a secret passage (94) leading to an area (379) containing a soul sphere.

Getting the soul sphere (see above) lowers the big box in the starting area. A switch on the wall behind the box lowers the SE section of floor, leading to a secret area (102) with lots of imps.

The slime river that leads east from the starting area flows into a small hexagonal room. There is a secret room (164) full of demons east of that room.

In the NE section of the map is a passageway with three NE-pointing corners in it. The middle corner's west wall adjoins a secret passage (191) that leads to an inner passage.

The main section of the underground passageway system has a section shaped like an H. Two passages that lead between the upper bars of the H are connected by a secret passage (193). The passage is originally raised, so that it's not accessible; a trigger in the P-shaped passage to the right of the H-shaped passage lowers it. Entering the passage from either end triggers the pillar in the adjoining passage to the south (374) to lower, making the red key accessible.

NW of the NW corner of the H are two parallel east/west passages joined by a secret passage (378).

North of the exit area is a red key door (which is revealed when you get the red key). Entering the area behind the door causes you to teleport to an area in the exit pit containing some armor. When you teleport back, you land in a secret sector (372).

MAP23Secret sector numbers: 235, 271, 293
Lunar Mining Project

On the east side of the central courtyard are four small rooms. In the room to the south of the northernmost one, a hidden door on the east wall leads to a secret area (271).

North of the central courtyard is a room with yellow key and red key doors, and a T-shaped platform (at the base of which is the red key). On the north edge of the T is a hidden door to a secret area (235).

The platform (293) containing an invulnerability artifact in the NW section of the map is a secret area. Jump onto the platform from the west.

MAP24Secret sector numbers: 6, 28, 30
Quarry

In the SE is a slime tunnel leading to a teleporter. On the south side of that tunnel is a secret area (6) containing a radiation suit.

In the SW is a U-shaped stairway. A section of wall on the north side of the bottom of the U opens when shot to reveal a secret area (28). To the north of that area is a lift (30) leading to some shells.

MAP25Secret sector numbers: 151, 163, 202, 316
Baron's Den

In the SE section of the map is an area containing a soul sphere, two revenants atop large pillars, and a stairway with a slime pool at the top. Walking on the stairway opens a wall, behind which is a secret area (151). This area is accessed from a room to its north: A switch in that room lowers a lift with a baron's face on it that is behind a door behind another lift. You have to press the switch, hit the lift to lower it, hit the door to open it, and run through.

In the room with a stairway running through a slime pool and two arachnotrons inside a cage, a door to the north leads to a room overlooking the slime pool. In the NW of that map is a short hallway leading to a secret area (163) with a cell pack.

In the NE is an oval room with a slime floor and a pillar that can be lowered to reveal a teleporter. The teleporter leads to a ledge in the room. Jumping over the north edge of the ledge lowers a wall in the passageway to the east of the room. There is a very small secret sector (202) in that east passageway at the point where it bends to the south.

In the passage to the SE of the oval room described above, there is a teleporter (316) to the east of the easternmost bend of the passage.

MAP26Secret sector numbers: 77, 317
Ballistyx

In the NW area of the map is a platform reached through a teleporter. On the north wall of that platform are two doors: One (near the NE corner of the platform) leads to a teleporter, and the other (near the NW corner) leads to an area (77) with a soul sphere.

The SW area of the map consists of a network of slime tunnels. In the room with the island (where the blue skull key is found) there is a hidden door near the northernmost point of the room, on the east wall. The door leads to a small room (317) containing light amplification goggles and a soul sphere.

--- Useful information about this level:

In the area with the platform containing sector 77 (see above), there is a lift leading to a soul sphere and a dead marine. There appears to be no way of reaching that area, at least in single-player mode.

MAP27Secret sector numbers: 69, 218
Mount Pain

Just west of the starting room is a hallway with stairs on the north and south sides. To the east of the south stairs is a passageway. On the west wall of that passageway is a hidden door leading to an area (69) containing some stimpacks and health bonuses. The stairs to the north lead eventually to a long spiraling tunnel. In that tunnel is a small room containing two torches and a body impaled on a stake. On the south wall of that room is a secret area (218) containing a radiation suit and a computer map.

MAP28Secret sector numbers: 45, 51
Heck

Both of the secret sectors in this map are small hidden areas off of the passageways in the maze of passages in the west section of the map. There are shotgun sergeants hidden in those areas.

Sector 45 actually consists of three separate areas, while sector 51 is only one area.

MAP29Secret sector numbers: 20, 91, 474
River Styx

The river from the starting point leads to a building entrance. To the SE of that area is a green torch which, when pressed, lowers a lift on the SW side, leading to an area (91) containing a soul sphere.

Beyond the entrance is a stairway leading to a small room overlooking a room with some walkways over a lava floor. On the east side of the stairway is a hidden door leading to an area (20) with some goodies. To the south and west of the stairway is an area (474) containing armor.

--- Useful information about this level:

To get the medikit on the T-shaped walkway in the lava room, get onto the E/W walkway to its NW, then run and jump.

In the hall to the NW of the lava room is a N/S section with a door at its eastern side that looks closed. In reality, the wall there is not solid. Beyond it are lots of bad guys.

MAP30Secret sector numbers: 51
Last Call

The only secret area (51) here is the courtyard where the boss shooter is found.

--- Useful information about this level:

To get through the initial pillar maze, follow the color sequence that you see in torches in the starting hallway, without retracing your steps: Red Green Green Blue Green Blue Green Blue Green Green Red Blue Red Blue

Using map compass directions instead of colors, start on the easternmost pillar that's reachable from the first platform and go to adjacent pillars in the following directions: N, W, N, W, W, S, W, W, N, N, E, E, N, N.

A switch to the north of the boss shooter creates a stairway leading to the top platform. To shoot the brain, stand on the first step down from that top platform.

Save your cells--you may want to use the BFG to clear monsters from the platform.

MAP31Secret sector numbers: 191, 208
Pharaoh

The teleporter near the starting area takes you to a large room. In the NW of that room is a sector with three pillars containing Hell Knights. That sector (191) is secret.

Leading north from that general area is a long E/W hallway that ends when it meets a N/S hallway. The northernmost sector of the N/S hallway (from which you can look down into an open area) is a secret sector (208).

To the north of the pier near the exit area is a room with lots of goodies in it. In the north wall of that room is a hidden door leading to an area (374) with a switch to Level 32, Caribbean.

--- Useful information about this level:

Note: There is a bug on this level that will prevent you from obtaining the yellow key (which should be in the room with the crusher, but isn't). Use the IDKFA cheat code to get the key.

Also note: There is at least one unresolved problem involving a floor in the area to the north of the throne room that doesn't lower properly. This could prevent you from getting 100% kills.

MAP32Secret sector numbers: 139, 141, 182
Caribbean

The NE room of the first large building contains a soul sphere. Running around that room is a hallway. The west side of the westernmost part of the hallway has a hidden door leading to a secret area (139) with lots of goodies.

Crossing the bridge that leads over to the second large building opens a door to the SW of the bridge, revealing a room full of revenants. That room (141), which also contains some rockets, is a secret area.

The inside of the small building NW of the first large building (182) is secret.

--- Useful information about this level:

The SE switch near the two teleporters in the final section (where the Cyberdemon is) opens the door to the exit. Hit the switch, jump in the west teleporter, and run over to the exit to get there before the door closes.