Lyrics
The other hidden ledge in the computer room is on the left-hand wall, near the back. As you run up the passage to the computer room, turn around the computers to the left, so that you reach the ledge before it rises again. You will find yourself on a wide gray staircase (O), which leads to a darkened passage containing a soul sphere on a column. The column can be lowered by pressing a switch on its south side. (sector 134)
The hallway (H) from the computer room to the rocket launcher room counts as a secret. (sector 167)
The small brown room with the backpack counts as a secret. (sector 159)
The east wall of the small brown room is a secret door (sector 174), indicated by a speckled texture. This leads to a gray room containing a chaingun (P). As you approach the chaingun, a hidden door and lift are revealed which provide a shortcut back to the beginning of the level.
There is a secret door (L) on the east wall of the room behind the blue door. It is not marked, but it opens automatically (M) as you step into the pillared room to the northeast. (The door can be opened manually too.) Behind this secret door (sector 73) is a room with a staircase. At the top of the staircase are a chainsaw, a box of rockets, two boxes of shells, and another staircase leading to a yellow door (N). Behind the yellow door is a room full of powerups including a soul sphere, a blue armor, and a partial invisibility. On UV and NM, you should probably take the invisibility immediately, since there are Sergeants and Imps in the surrounding courtyard (U) who can be difficult to shoot (due to the brown fence texture which obscures your vision).
The long tan passage to the secret exit counts as a secret. (sector 51)
In the room with the secret exit, the north wall is an elevator (Q). This leads to a platform overlooking the donut-shaped walkway. There is an Imp and a box of rockets here. (sector 40)
