How to find the secrets in PARADOX.WAD:

There are 7 "Secret sectors" on this level.  Some areas of
the map contain multiple sectors.

You begin the level in a small room at the middle of the
eastern edge of the map.  This will be the starting point
for the instructions that follow.

Exit the room, and turn right.  Walk north up the stairs
and take note of the tall pillars that you're passing on
your left.

Secret 1: Activate the pillar that is the third pillar on
your left as you go up the stairs.  This pillar will drop
down, revealing a Soul Sphere ("Supercharge").  Pick it up
to get credit for finding this Secret.

Continue north to the top of the stairs, then turn left and
walk west down the path to the wide wooden door up ahead on
your right.
Go north through this door, and you'll see a long, wide
hall ahead of you.  At the far (north) end of the hall is
the yellow key on the ground.  Grab it.  (And prepare for
an attack from teleporting monsters.)
Take note of the semi-circular room where you pick up the
key.  At the north end of the room, nestled in the middle
of the north wall, is a green torch.
Activate this torch like a switch.  Behind you, in the east
and west walls, panels will rise up to reveal switches.  Go
and Activate both switches.  The panels stay open for only
a few seconds.  (If you don't get to one of the switches in
time, simply Activate the torch again, and then go to the
switch you missed.)

Secret 2: The switches you just Activated have opened doors
in the east and west sides of the long hallway nearby.  Go
look for the open doorway in the middle of the west wall of
the hallway.  Stepping out onto the ground beyond this door
counts as a Secret discovered.

You can either re-enter the hall through this doorway, or
walk around the outside, to the south end of the east wall,
where you'll find another open door.  (On the way, look for
a BFG-9000 in a niche in the north wall.)
Go back to the wide wooden door at the south end of the
hall, and leave through it.
Turn right and go west, all the way to the corner, then
turn south and go up the stairs.
At the top of the stairs look for a yellow-keyed door on
your right.  Go in and turn right.
Ahead is a rectangular chamber.  At the far (north) end of
this chamber is a partition, which will rise up into the
ceiling when you approach it.
Behind the partition, on the north wall, is a switch.  Go
Activate it.  (This will lower a barrier that blocks access
to the teleporters in the small chamber in the middle of
the map.)
Go back out through the yellow-keyed door you opened a
moment ago.  Go straight ahead (east) across the bridge to
the structure ahead.
You'll see a central room in the structure, with 3 teleport
pads arranged in a rectangle on the floor.
Walk up the steps and through the doorway, but do not step
onto the teleporters, yet.

Secret 3: Turn right, and just inside the doorway, search
the wall just to the right of the green torch.  When you
Activate the wall, a section opens, allowing you to step
through.
Walk through this opening, and on to the ledge beyond, to
get credit for finding this Secret.

Turn left and carefully walk a pace or two to the south
edge of this ledge, being careful not to step off; Then
turn all the way around to face north.

Secret 4: Run north off this ledge, and over the small gap
where the steps are, to the next ledge just on the other
side of the steps.  (Remember that "Run" in PC Doom games
is typically enabled by holding down the Shift key.)
Walking around on this ledge will count as a Secret found.

(Note that if you cross the center part of this ledge, a
section of the nearby northwest battlement will drop down
for a few moments, then rise up again.  Stepping on this
lift, or walking around on top of the northwest battlement,
will not count towards your Secret score.)
Step down off the ledge, and walk along the interior path,
around to the east side of the central structure.  Leave
this structure through its east-side door.
As you walk out this door, stop and turn right, to face
south.  You'll see a structure ahead, which is located at
the south end of the east side of the map.  You'll be
looking towards this structure's north wall.
Walk around the outside of that building, and go to its
southeast corner.
With your back against this corner of the building, turn to
face southeast.  You'll be looking towards a nearby stone
wall on the east side of the map.
Notice that a portion of that wall juts out a little.  Just
to the left of this part of the wall is a false, intangible
wall panel.
Below is a diagram showing the southeast quadrant of the
level, and the location of the false wall panel that marks
the entrance of a hidden passage leading east.


                ___     ()  |
               /   \__  ()  |
              |       |     |
Southeast --> |      _|     |
structure     |     |  _()__|
              |     | |
               \___/  |
                      : <-- Intangible
              -----. |      wall panel
                   | |
                   | |
                   |_|


Secrets 5, 6 and 7: Step east through the false wall panel.
Walk down the winding tunnel, to an oval-shaped room to the
east.  Kill any monsters there, and then slowly walk back,
west, through the tunnel to get back outside.
(There are 3 Secret sectors that cross the floor of that
tunnel.  Walking slowly through the tunnel will help ensure
that you touch all three, and thus get credit.)

The above areas are the only "official secrets" on the map.
Note that just to the south of the level's entry point is a
small hidden chamber, which contains a rocket launcher and
some ammo.  This area is only accessible during Deathmatch
games, and is not considered a Secret area.

To read about and/or download a demo of this level, showing
how to access all Items and Official Secrets, click here.