When you reach this level you will possess a chaingun. The one in front of you is to be picked up if you get killed and start on a new life instead of reloading. Turn around and open the elevator door behind you, push the wall block and enter a quiet castle like environment. The amount of ammo and health lying around is a little disturbing though. Open the secret doors in the three remaining inner corner rooms for even more powerups. Locate the Gold Key in the northern part of the floor. Make it to the south and take up position in front of one of the gold key doors. Open the door and jump at the Silver Key and back again, you need it to use the short cuts across the parallel corridors. Now General Fettgesicht will be coming after you. Know that the enemies in the outer rooms as well a those in the central one may come at you at any moment after the action starts. Concentrate on fighting Fettgesicht but don't forget to be on the move and fight off the legions of enemies that are coming at you from every angel. Be sure to be near the reinforcements whenever necessary. The secret outer corner rooms hold extra 1-ups plus treasure.