Retreat to doorways to kill rats and use doors to kill them by letting the door fall upon them. They are tough little gerbils. Good eating though (Yech!).

When you come down the stairs, a secret door will put you into the area you want. The secret door is one space to the left of the writing you'll see. Beware that if you exit and then re-enter the secret door, a couple of mean rats will ALWAYS be regenerated here. Go left and follow the hallway and look for a two space pillar. Search all sides for a secret button. Press it to open a secret chamber. Then go all the way back past the secret door to the stairs. You'll come to a "turn-around" spot. Turn around and go backwards through it and then turn around again and go forward. You'll understand it.

Find your way around until you come to a grate-doorway with no apparent means of opening. DON'T PULL THE SWITCH! It will drop a chest into a pit, which is extremely difficult to retrieve. From the gate, go right and follow the paths until you see stairs leading up. Go up a level and find a trap door. "Fall-in" and you're now on the other side of the grate and you can get the chest and press the button on the wall to open this grate now. Continue down the hallway until you come to a room where fireballs are being fired at you from the wall. Don't worry, they only fire at you when you take one step, so save your game here and heal everyone. Then take one step. "Boom". Heal everyone. Take another step. "Boom". Heal everyone again. Repeat this until you get out. Now go left when you get the chance and get the rope you find laying here (useful for going down into traps without inflicting damage too bad Rom Chip didn't find a way to go back up the traps with the rope). At the end of this hallway is a switch and in the room is a needed key. If you see a CORBAMITE laying around, be sure to get it. Go back to the fireball room.

At the Fireball room, don't worry as they only fire "fireballs" if you're moving away or towards the fireball shooters, so just walk past them to the right exit and keep going. There are only two places you can go to here now. One is a RAT NEST or a door, which allows you to continue. The rat nest door is to the South and the other door is to the North or right. Put your CORBAMITE in the slot to open the door. Here's the stairs down to a room with another key. If you walk down the dead end corridor to where a skull is on the left wall, you can use a skeleton key to open a secret chamber housing stairs which will take you all the way down to the lowest level. It's good for getting out or coming back up looking for food and water. You could go and unlock it in case you come back up later using the express stairs... heh heh!