- slide 1 of 4
A Little Routine Maintenance
Okay, we're safe for the time being. You can listen to the little class on the AR2 if you want. The important stuff is just a little joke from the braggart rebel and that the alt-fire is a one hit kill for the hunter. Walk past them and meet up with Eli. Then ride down the elevator with Eli and Alyx to get to the rocket. As a side note, this is the time to put the gnome inside the rocket. Go up the little ladder and put it into the side compartment with Lamarr. Just wait it out until Magnusson asks you to take care of the alarm. It's not just crows, but you should have figured that out by now.
Go down the hatch and step into the lift. Ride it down and then move over to the steam flow. Turn the winch to kill the steam and give you access to the door. Uriah is apparently too busy to notice you, so you need to throw the emergency override. Break the glass and pull the switch in blatant defiance of Magnusson's note. Uriah will come fix the door and let you through to the secondary silo. Go through the back doors to hit a loading screen.
- slide 2 of 4
The Access Point
Once you regain control, you just have to push forward. Move up to the rebel and confirm that these must be some really big crows. The door is sealed, so we need to crawl under the little stairs and get into the room via the vents. Quickly move to avoid the hunter's darts. Just come around the full way to pop out.
I suggest that you just use the alt-fire on the AR2 pulse rifle. You should have 3 shots, so you might as well use them. There are 3 hunters, but they should attack one at a time. Don't worry about saving the rebels. You can't take them with you anyway. If you miss a shot, then just peg them with the magnum to kill them. 2 manhacks also come through, so just pull out the gravity gun to knock them out.
The path out of here is through the catwalk. Climb up a bit and jump onto one of the shelves. Go around to the shelf in the back corner with a crate sitting on it. Jump up on the crate and then up to the catwalk. Move along the catwalk and get to the steam. Turn the winch and then climb up to the vent system.
- slide 3 of 4
Fight for the Silo
Pop out and notice the Combine flare. Use the shotgun to nail the guy charging toward you, then move up to get away from the turret. Pop out to bait the 2 guys hiding here, then blast them when they walk around. Be careful, since one is a shotgunner. Once they're dead, pull out the gravity gun and knock the turret away. Rush forward and notice that the left tunnel is covered by a turret. This means we have to take the right one.
Go out into this water-filled area. Use the pipes for cover to pick off the Combine. You really need to keep your head down, since the turret in the doorway can really hurt. After you've cleared out the first wave, rush over to the left side to get away from the turret after you've grabbed some supplies. Go ahead and knock over the turret facing away from you. When you're ready, move toward the door. If a few more Combine come out, then nail them with the shotgun. Once you get to the doorway, just use the gravity gun to take out the turret.
Advance up the ramp but be ready to run when you reach the exit. 1 soldier and a hunter will come through the door. Blast the soldier and then start pumping shotgun rounds into the hunter while you fall back to the last room. It should get stuck on the door and give you time to reload. Pour the other 6 shells into it and it should die.
Go up and grab some of the supplies from the side office. You'll come up to a broken door. Blast the 2 Combine that try to drop down and ambush you. Then go into the side room and climb the broken stairs. Drop down and then jump into the water. You'll come out of this utility tunnel into the secondary silo.
- slide 4 of 4
Sealing the Silo
Climb out and move around to the first ladder. Climb up to the second level. I suggest you just rush around and climb up again to get to the 3rd one. Blast the 1 soldier who should be on this level. Move around the circle and use the AR2 to take out the 3 on the level above you. Climb up again to get to the very top. If you're moving fast, you should arrive as a Combine dropship should start sending in new soldiers. They'll rappel in. The first one will probably just go down below you, so don't worry. The other 2 will land on the top. Blast them and cut over to cover behind all the shelves.
There's a machine gun in the office and 2 extra soldiers covering the position. Get to the shelves and crawl through the little mess. Jump up and through the next set to get to an office area. Get inside the secondary room and wait. Reload your weapons and kill the manhacks that should be flying in right about now. When you're ready, lean out from around the corner and lay into the gunner. The shotgun works well, the pulse rifle is good too, and a well thrown grenade might work. Regardless, just take out the gunner and the guy next to him. Then charge up and crawl through the hole in the glass. Kill the 3rd soldier if he isn't on the gun already.
Throw the switch by the gun to start sealing the silo. Then jump on the machine gun and use it to take out the next set of soldier rappelling in along with a few man hacks. You'll get a quick headache from the advisor outside, but we're sealing him out. Alyx should bring some reinforcements in as the silo seals. There should be Uriah and a medic. They should take out any stragglers in the silo.
If Alyx gets stuck, just reload and give it another shot. She should contact Eli and get Uriah to open the top door. Follow her out until you hit the loading screen. Go into Eli's office and just wait for a bit. There's a long scene and you might as well enjoy it. Aperture Science is also the company in Portal, so it looks like they're putting the game into the same universe.
Once it's done, Magnusson will come in and request you for a new mission.