A playthrough of Duke Nukem 3D Atomic Edition (the original DOS version, not Eduke32), attempting to get every secret in the game. This is shown in High Definition.
Comments: This has more secrets than any other level in the entire game, with a mind-racking 14. Technically, this was going to have 18 secrets, but due to Build engine limitations (you can't have an underwater sector also be a secret) it was cut down to 14. I show all of them, even the unofficial ones.
This playthrough uses no saves except between levels, and is played on Come Get Some difficulty.
#1: Into the fire: 00:18
After you escape from the sub, jump on the part of the sub that's on fire at the top. A secret passage will reveal a first aid kit, an Atomic Health, and some armor.
#2: Crack in the wall: 01:00
After you escape from the sub, go into the underwater cave and shoot at the huge crack guarded by Octobrains. You'll find some pipebombs. After accessing that, head to the area with the captured babe and the waste barrels. Blow up the barrels, and you'll reveal a passageway to the surface.
#3 & #4*: Fire in the hole: 02:17, 01:06
At the gun turret holes at the start, destroy the turrets, then jump into their respective holes and open the secret walls. You'll find 10 RPG rockets and a Holoduke, along with a hilarious message.
#5: Secret wall : 03:06
When you enter the building, there is a secret wall. Open that wall to access the bunker inside the window the troopers were shooting from to find a chaingun cannon.
#6: In the slime: 05:04
In the conveyor belt area with the slime, there is a box of ripper ammo hidden behind a secret wall.
#7: Atomic health in the pipes: 05:10
In this room, there are two pipes. One contains a secret, one doesn't. I'll leave it up to you to guess which does.
#8, #9, & #10: Triple secret!: 07:45
In the rocky cliff area high up, there is a crack in the wall. Blow it up to reveal an apparently blind Assault Trooper. Blow up the consecutive cracks to reveal a pathway to the start. Each crack reveals a secret.
#11: Hidden scuba gear: 08:13
In the area where you press the button to open the underwater door, press the rock area to open a secret wall revealing a much-needed scuba gear.
#12: Leap of Faith: 08:34
In the same area, go to the top of the cliff and jump into the dark hole. Look further into a hole to find a secret. You might need some night vision goggles to see it, but I've noted the location on the automap.
#13: Between the Cogs*: 09:56
In the underwater area with the broken teeth gears, go in between the gears (by waiting for the broken tooth), then let the gear take you around the shaft. There is a First Aid Kit on the other side. This is difficult to do without getting crushed, so be very careful.
#14: Armor behind fake wall*: 10:10
The area beyond the rotating gears has a fake wall. Beyond the fake wall is some armor.
#15: Hidden teleporter: 10:34
Beyond the rotating gears, there is a flow of water heading to the area with the moving platforms. Stop in the middle of the flow to find a crack. Blow up that crack to reveal a teleporter.
#16: Behind the platforms*: 11:47
This is a tough one. In the area with the platforms, there is a button that moves the platforms that is revealed after you press a switch. While in the water, shoot the button from afar to move the platforms, go underwater, and you'll see a hidden cache behind the platforms. You have to be quick to get to the hidden cache or risk being crushed.
#17: Radioactive Power: 12:50
Near the end of the level is a vent which can be broken, but is really hard to get to. If you can perform an incredibly tight and well-timed high jump, your reward is two Atomic Healths (I was able to do it twice because I'm a showoff).
#18: Secret Level: 13:56, accessed at 14:28
In the final part of the level with the slime flow, in the middle of the flow, there is a crack in the wall. Blow up that crack to access the area with a secret exit waiting for you!
*not counted as a secret.