Here's a play-by-play of the demo included...

Start in the Pulse room
Go out the north door into the Stone room
Go thru the lion door into the Brick hallway
The Brick lift
The Health room                                 (notice the backstab window!)
Thru the Blood curtain into the Blue room
The Blue room                                   (notice the blue lift is down)
Go out the Brick hall and thru the Stone room
Thru the door into the Panel Hall, go right into Red room
Go up the Red lift to the Wood room
Go down the stairs to the Stone sniper room
Drop down and go back to the Panel hall
Follow hall to the Blue sniper room
Go back to the Stone room and activate Stone lift
Shoot that barrel to let lift go down
See the pretty crates...
Activate the skull switch to start Crusher      (notice the Barrels blow up!)
Notice the Difference in floor texture by the Berserk platform
                            
                            *** how to get the Plaz!!! ***
Notice the trick to getting out of the barrel trap!!!
Go thru Stone teleporter
Notice the stairs to the Berserk platform have risen!
Get the Light amp goggles and Inviso Sphere
                            
                            *** how to get the BFG9000! ***
Go to the Blue Sniper room and thru the secret panel
Shoot Bookcase to open
Hit Skull switch
Notice the 'fence' (rising stairs) has appeared
Go get Radiation suit from cove in Red room   (Notice the Health!)
Walk the fence to get BFG!!!  (you don't HAVE to use the rad suit to succeed)
                        
                        *** Now the EASY way to get the BFG!!!! ***
Go thru the Plaz tele
Run to Brick tele and go thru
turn 90 degrees right
GET BFG!!! (if someone didn't spot your little scheme and wait there first)

       *** A walk through of the items (except the inviso and lite amp)***
Berserk pack
Blue armor
Health
Megasphere
Rocket launcher
        
        *** Show some little tricks of how to know where enemies are ***
Crates go down from walking over stair in Brick Hall
Crates go up from walking thru Panel hall at end of Red room
Wood lift activates from any side
2nd last step in Wood stairs stops the crusher (you CAN create a dead end!)
walking up or down the Berserk stairs causes the light level in Stone
       sniper room to switch from 0 to 255

                     *** the teleporters!  all of them! ***
Notice that the barrels I shot into the teleporter earlier are now in the 
       Red room (at the destination) and they blow up when I tele onto them!
Notice the Color Scheme of the teles match their destination! (mostly)

                       *** the Flag on the Brick lift ***
The blue pole goes up and down with the Brick lift!!! You can see this from 
       The Blue room and the Blue sniper room! (and you can shoot thru the
       Blood curtain! hehehe)

                           *** How to Frag Yourself ***
If you play against me, this is a requirement (It's my DOOM handicap, Ten
       Suicides per game)

hope this and the txt file answer any questions (probably boring you to DEATH
by now!).  {Except the usual, "How'd you get to be THAT EVIL!?!?"}
Ok lady, I love you Bye Bye!