1. Destroy inlet pump controls: medium 
2. Destroy outlet pump controls: medium 
3. Destroy master control console: medium 
4. Use radio to contact Jack Wade: hard 
5. Minimize scientist casualties: easy, medium, hard 

Four to five guards will be in your immediate presence, kill them, and try not to get touched. It's possible. Then just follow the path the only way you can. You'll pass through two doors before being able to veer off the beaten path. Go downstairs to an area with two computers, a scientist or two, and some ammo boxes. Blow these up the computers, and then the boxes, for ammo. There is a pathway to another similar area; you can take it or the stairs, both lead to the same place. There are two main computer set-ups down there as well. Blow them up, and objective A will be met. Make sure not to hit any scientists. 

You'll come to an opening. It leads to what seems like the bottom of the entire cavern. There should be a guard or two, so kill them off. A winding path leads in a spiral fashion along the right side. Take this path (there aren't any other choices anyway). Knock out about three military personnel along the way. At the top is a guard and a door. From this door, a handful of soldiers will emerge. Stand back, wait until they show up, and then blow them the pieces. Make sure to stand back and off to the side to stay unhit. 

A circular cave with a central pillar and about three to four guards and lots of ammo boxes are next. Nail all of these guys and grab some ammo. Follow the path until you have a choice of going down some stairs to your right or continue upstairs. Go down the stairs and run straight down the hallway killing everyone until you reach the end. Guards will shoot at you, so turn back and go back up the stars you descended. Now run along the top of the bridgeway blowing everyone away. 

You'll reach an entrance, but don't go inside yet. Retrace your steps to the very door that led you into this area in the first place, and then walk down the stairs and do a 180 degree turn. Follow this new path around until you get to a cavern with lockers in it. The lockers will be on your right side. Blow up the lockers. Behind them is a secret path to another cavern. Lockers on the other side will block your path, and you'll have to blast them, and unfortunately draw attention to your arrival. You should have two ZMGs by now. Use them to blast through the second set of lockers. Guards on the other side will take note of all this racket, so be prepared when you arrive to shoot at anything that moves. There are initially about three. Two to three more join in from a stone staircase on the left. 

Once the area is generally clear (note: if you stay in one place too long, more soldiers will come), you'll see a big pump on the left, surrounded by two computer consoles. Blow these consoles up and the one to the left of the secret entrance, and objective B will be met. 

Walk up the stairs carefully. No one should be in sight. That should worry you. To your right is an automatic machine gun and two guards. Move out about a foot quickly to get the guards' attention and then quickly move back down the stairs. If done skillfully, the machine gun won't react. The guards will come to you, and you'll kill them. When the coast is clear, angle slightly to the right so that you can hit the big gun. Make note of the locked door to the right for which you'll need a key for it). Take the door to the left, instead. Now you have to carefully clear the guards from the paths. Wipe them out and you should pick up a few security cards along the way. 

You will next approach an opening guarded by two soldiers with sunglasses and berets. These guys have RC-P90s and carry code cards B and C. You're near the heart now. Kill them but don't enter the doors behind them. 

You're about to enter the radio room. You must not make any big explosions that could destroy the radio. Take a look around real quickly and then pull out. There are a few guards inside, one with a RC-P90 to your right, as well as a piece of body armor on the crate. Go through the first door, open the second and peek around. Kill any stray guards and back out. Do this until you're sure no one is left but the RC-P90 guy on your right. In the distance are the radio, scientists, and three soldiers who stand right in front of explosive barrels. They can easily shoot at you from the right, so shimmy to the far left wall and turn around from where you came. The RC-P90 guy will start shooting, and to need to take him down from where you stand. Now, use the leaning technique to peg each of those three soldiers near the radio. Use the site on the rifle, too. Once the area is clear, go to the control room and radio intelligence. After you've send your signal, put a timed bomb on the explosive barrels, and another objective is met (Objective C). 

Now get out. Go back to the room with the strange blue door you couldn't open. You should have picked up a key to open it by now. Two guards will be waiting for you on the other side. Kill them. Go through the next door on your left, the exit. Janus will appear and say something like, "Too slow, eh, James?" Then an automatic machine gun on the ceiling will start blasting you. Kill it as fast as possible and enter that area because visitors will appear behind you. Run through that tunnel, find the elevator, and you're out.