Enter these codes while playing.

Effect                Code
God Mode              DAVIDBRUS
All Ammo              MIKEKOENIGS
All Ammo and Keys     SCOTTHOLMAN
All Map               DIGITALCAFE
Invisibility          MARYBREGI
Invulnerability       ANDREWBENSON
No Clipping           CHARLESJACOBI
Strength              DEANHYERS
Position on Map       KIMHYERS
Invulnerability       LEESNYDER #1 #2
                      Where #1 is 1 and #2 IS 1-5
Radiation Suit        ALLEN
Bootspork             JOELKOENIGS
Additional Map Info   SHERRILL

In the second level there are two refridgerated storage rooms. In the second one of these rooms there is a secret vent with some cool stuff inside it.

Get on the turbo lift in the back, you want to stand in front of the big set of crates toward the left. You must stand right on the edge of the power lift. When it goes up run forward an youll get on top of one of the crates. You'll notice that one of the panels on your right is different than the others. Open it, then follow the vent. At the end you will find a small blue room with a really big gun.

In level 5, as you walk up the stairs(before you go down again), at the top, there will be a light to the right. Open it, and there will be a flemoid and a yellow key. After you get rid of the Flemoid, and get the key, turn around and go to the northwest corner from where the key was. It's a door. Inside, the will be a stream. Go right. At the end is a waterfall. Go down it. There will be another flemoid in the room you are in. After you go out of the room, you are in the boss's room.

In each level there are a number of hidden doors. Here is an easy way to find them.
After you completely explore a level, press TAB to view the map. there will be short yellow lines on some walls on the map. Most of the time, those short yellow lines show where hidden doors are. Just walk up to the place on a wall where a yellow line was shown on the map, and press the space bar. If you are at the right location on the wall a hidden door will open. Alot of times there are some health and weapon rechargers behind the hidden doors.

On level one, when you're in the big room with the spaceship there will be a small door. Go inside. When you enter the room , there will be a flemoid guarding a blue key. After you kill it and get the blue key, go to the back of the small room and press the spacebar. Then, you get a tri-barreled zorcher.

In the room where you win the game, go down the hallway and to the right toward a painting. When your up in front of it press the spacebar there will be a flemoid and a 100 + armor bonus