Level 1
Slipgate Complex

Level 2
Castle of the Damned

Level 3
The Necropolis

Level 4
The Grisly Grotto

Level 5
Gloom Keep

Level 6
The Door to Chthon

Level 7
The House of Chthon

Secret Level
Ziggurat Vertigo

In this level, you'll immediately notice something odd about the way you're moving. Your first impression may be that "slow motion" has been turned on or that there's something wrong with the game. Ziggurat Vertigo, however, means reduced gravity. Although you can't fly, your newfangled jumping ability is the next best thing!

When jumping, watch where you land - the lava is lethal. If a jump is carrying you too far in the wrong direction, use the arrow keys to make small corrections.

For those into deadly exploration, there's a secret room hidden in the lava.

Secret Area 1
Grab the Pentagram of Protection and the armor that are floating in the entrance to the ziggurat. Turn around and step into the lava beside the bridge. Move forward until you are in the corner where the bridge and walkway meet, and then dive. Your initial dive often results in a major bounce straight up. Use the Z key to dive. Once you're under the lava, swim to a spot beneath the bridge and then go forward (away from the ziggurat). You'll emerge in a room that contains a quad damage power-up, a health kit, and a teleporter to take you back out of the lava.

A quick scan of this area reveals that the correct path is upward. Check out the tops of buildings and all platforms for enemies and power-ups. Although you can make solid progress by jumping up through openings, the fastest way to the next level is the elevator. Waiting at the highest point in this area you'll see a health power-up and a wall-mounted emblem. Push the emblem to open the gates to the ziggurat. Return to the main level, clear the ziggurat of enemies, and push the second symbol. Now a new elevator on the ground level is accessible to you.

Find and push this pair of emblems.

A shambler and an army of ogres and scrags guard the third emblem. Be careful: It takes only one solid hit from a shambler's bolt to fry you. It’s wise to attack any shamblers from a distance and backpedal whenever they toss any bolts your way. The best weapons are the nailgun and super nailgun.

If you find yourself repeatedly dying at the shambler's hands, look for a different place from which to attack.

By the time you get the items behind this panel the enemies are all dead. Still, never walk away from free stuff!

After pressing the third emblem, return to the walkway in front of the locked door (silver key required). Below you'll see a new series of walkways and platforms. It's there that you'll find the silver key. Use it to unlock the door and make your way to the level's end.

Secret Area 2
In one of the hallways beyond the locked door (silver key), you'll note one panel that is darker than the others. Strike it to obtain some additional ammunition.