The first thing you need to know is that when you pull the lever that is in the room, it will spawn a large number of nazis, as well as some super soldiers and heavy soldiers. If you decide on fighting them, the best way to do it is by using the lower floor that you came through as a base and killing them from that location, or the hallway we used in killing the two commanders. However, it's entirely optional and you'll waste not only ammo but time, health, and armor by doing this. The best thing to do is to simply run to the cable car and wait until the hatch leading outside Castle Wolfenstein opens up by hiding behind the stairs and walls inside the cable car. Then interacting with the lever inside the cable car to head on out of the area.
Whichever you do, once you start going down via cable car, you will be intercepted by a group of nazis in an opposing cable car going up to Castle Wolfenstein. They are optional to fight as well, and it's a better decision to do the following: when both cable cars stop, there is a hatch in front of the lever that started the cable car that opens up. You have to climb up it and then interact with the cable car railing, and you will jump into the next cable car.
Once you're in the next cable car, there is a small window in the upper right part of the building you are fascing that houses a commander. However, trying to look at him will most likely cause him to sound the alarm, so it's better to go around and silently try and kill the few nazis that are located in the building. On the other side of the building, outside, there is a Gold piece that you can pick up. Once you've killed the nazis as well as the commander, there is a lever that you will have to pull in order to start the power for the cable cars.
Once you pull it, another cable car with nazis will come up to try and kill you. You can ignore these nazis as well and instead jump through the window to the right of the lever to go back to the main cable car. However, if you want to fight these nazis, it's best to get the schockhammer and use the stairs between the lower floor and second floor as cover as most of the nazis will simply try and run through the area to try and get you.
Go back to the cable car you jumped into. What you'll want to do as soon as this happens is crouch behind the lever and wait for the hatch above it to open up. When it does, climb it, and a cutscene will happen. Once it does, look to the left of the cable car and you can open the door. Swim through the area until you can get on land, and get out your handgun. Kill the two nazis and go up the way they came down from. Slide through the small area and you will be able to pick up another Gold piece.
Continue down the path and look out for a wall on the right side that can be climbed. Go up it and kill the nazi that's there. Then, look over the left railing and kill the commander. Crouch and slowly go forward to kill the next commander located in the small cave up ahead. Then, go back out to the balcony and go right to find another climbable wall. You'll find several more nazis in this area. Kill the first one patrolling in front of you, then kill the one coming down in the far right area. Go through it and then kill the one patrolling that level further up ahead. Wait for the heavy soldier to start walking towards the entrance to where we'll end up, and then kill the nazi at the top of the stairs. Turn to the left and kill the commander, but be careful, there is a super soldier in the area. Pick up the machinegun that's behind you, kill the 2 nazis who are coming up the cave entrance where you came from, and kill the super soldier by blasting his power source, opening his chestpiece, and then shooting him there.
Continue walking along the path, however, be careful, as 2 flying sentries will coming from deep inside the cave area. Kill them and go to the elevator. Before interacting with it, kill the 2 nazis who are coming from the cave area you entered from. Once you're all the way up, look to the left of the wall in front of you and you'll find a climbable wall. Go up it and you'll find a Gold piece on the table to the right. Continue along the path, and you'll find yourself underneath the bridge area. Keep going across the bridge, jumping across the gaps until you're on the other side.
Before opening up the door in front of us, look behind you and look to the left. On the ground will be some carbdoard boxes, and on top of those boxes will be another Gold piece. Go out the door and kill the nazi patrolling the bridge area ahead. There is one up on the balcony area near the machinegun, as one as patrolling the area behind there. On the other side of the bridge area, there is also one more nazi. As you move towards the middle area, two more flying sentries will spawn. Kill them and continue onwards through the next door. Quickly interact with the hatch and be prepared to kill a few more nazis once the door opens up. Once they're all dead, go to the registration booth and look into the safe that's on the right wall. Inside will be a Gold piece. There will be a nazi on the stairs that go up to ground level, so be careful when you're going up.
When you start to walk out, several nazis will appear on the balcony and on the level that you're currently on. You can hide behind the dumpster as cover, however, and it will help in mitigating a large amount of damage. Once all the nazis are dead, when you try to walk up further into the level, more nazis will come out of the buildings on the side of the main entrance. Once they're dead, you can go and interact with the building in the middle to open the door to it. Once inside, you can go up hatch in the middle, but be prepared, as a large fight is about to happen. First, 2 nazis, heavy soldiers, and flying sentries will spawn. After that a super soldier will come out. Once he's killed, pick up his machinegun. After a moment, a mechanical dog will jump out from between the two cars. Simply waste your entire clip of machinegun ammo into it, and it will die. Try and move towards the side and then back as he's chasing you, as it will help you hit him without being hit yourself.
Once he's dead, There will be another two waves of nazis that come out from the left and right sides of the area behind the cars. Kill them and then climb the ladder on the left side. Continue along the path until you reach the tavern. Interact with Annette, and you will enter the tavern. Once inside, go upstairs and you will find a Nightmare Level bed as well as the last Gold piece for this level.
Interact with the door next to Annette, and then stock up on any supplies in the tavern. When you're ready, interact with the basem*nt hatch. A large fight will now happen with a large number of nazis and heavy soldiers. The best thing to do is to go near the fireplace and snipe the nazis with your guns when they try to go through the windows. After a while, you'll be able to interact with the bastement hatch again. When you do, Rudi Jager will bust through the main door in a very large super suit.
