That door is locked! Turn around and push the elevator control and kill the two SS. To get through the next room you must push the central block backwards, thus blocking the path back to the entrance. Then move on and clear the blue stone area. There is extra ammo in one of the cells. When you get to the first purple room, you will be able to notice the Silver Key past the well to the right. A secret door lets you get to it. In the room with wooden barrels, things get very hard. Move through a gold key door when it is open for a short cut to that key. Otherwise prepare for even more heavy action in the blue brick rooms. There is a 1-up in this area. Another 1-up plus the Gold Key are hidden inside the vine maze. Eventually you will make it back to the start by passing through secret doors. Don't forget the chaingun. Then get ready for the final countdown with Dr. Schabbs. One method is to run to the left. Wipe out the mutants and get into the next room with powerups. But look out for the mutants behind the columns and in the 1-up room. If necessary get to the north end of the outside area for more powerups, and mutants.