This is a safe drop for you and the civilians as you return to Alyx. Kill the barnacles with your Shotgun as you advance. Three pieces of debris later, the lift stops. Now you will have to make another bridge using the energy balls. There will be some soldiers out here this time and once you actually walk out a Combine Armored Car will come out and launch some missiles at you. Once this happens continue on forward through the doorway. Then climb into the new vent, use something to give you the height, the table or explosives drum works fine.
The crate on the right holds a head crab. Wait for the glass lift to come back, cross it to get to a combine energy dispenser where you can heal up. Slip between the trains here on the left. Continue to the left and you will see the tube with the Roller Mines. So if you need to, this is the best time to gather ammo, health, and position stuff.
Continue farther right to find this supply crate. Once you kill them you will come to another bridge, knock the wooden block from the reel to let it fall down, then cross over and go in and to the left hall. Finally you get some real weapons. Head on out and meet up with Barney. When all the rebels are inside the hideout, join them in there. Head towards the stairs and the door will do the beeping thing again, the Combine should come down and be killed by the Hopper.
There will be a car through what looks like a window or door of an area and a supply box to the left of it, go in there and knock the car out, covering a second Ant Lion pit. In the vent you can pull across some health and a flare, the flares aren't super useful, but they do help, just pull it or pick it up with your use button not here though and it will ignite. Continue through the hall here and into one of the rooms that has the energy balls shooting out at you. Here you will have to sprint across the bridge at the right time. Once all of the enemies are lying on the floor, their blood pooling inside their armoured suits, you have to extend yet another bridge. Hope you guys enjoyed this walkthrough! There will be a small oven like door on your right that you can pull off with your Gravity Gun, do so and climb in. Again, make use of Alyx's talent and knock all the boards you can off as quickly as possible and just retreat here and pull Zombies and Zombines back and conserve ammo.
Jump in here and then continue to the far left. Alyx will say how unstable the place is and say she doesn't want to be around much longer. Advance slowly using the small area in the wall as protection, you cannot knock over the turrets so just advance, kill the Zombies, and eventually you will reach the end and you can pull the plug on the gate and the turrets will be deactivated. Kill the Combine soldiers that come out and continue down the hall and out. After you regain control you will see the Stalkers are going crazy and Alyx is trapped. Some more Zombines will be in here but grab the explosives and do as much damage.
Next to Alyx is the door, blast it open and jump down, Alyx will follow you and then continue under the wall and proceed to Chapter 3. Take them out and run back to the hideout. Before dropping down pull up the two Hoppers closest to where you will drop, then drop down and pull up the last one. . You will drop down another floor into some water, continue forward under some piping and other junk, once you surface walk up the walkway and shoot the Black Head Crab on your right then you will see a small hut like thing, inside is another Black Head Crab. Smash the crate blocking the doorway to get behind the green car. Open the door and destroy the planks that block the passage 147.
The Orange Box - Half-Life 2 Episode One Half-Life® 2: Episode One is the first in a series of new adventures created by Valve that extends the Half-Life® 2 single player experience. As zombines are apt to do, one of them blows himself up, opening the glass wall to the right. Continue onto the right and you will see some turrets and a lot of dead Zombies. Descend the stairs all the way to the bottom to find this zombie-guarded supply crate. After she shoots down the ladder jump up to it and continue over the wall. Then shoot the right one as normal and cross the bridge.
More is on the other side of the fence, left of the supply crate seen ahead. Continue forward and you will come into a room where there are one of the Combine gates blocking your way and in the other room you see some Stalkers, one fiddling with the computer console and another using its lasers to do some damage to something. To conserve ammo here I just used the gravity gun to knock back and kill some of the Ant Lions, since it helps much more then wasting your ammo on a limitless enemy. Finally you will come to the end, drop the vent lid to activate the trip-mines and clear the room. First you let Alyx through the gate by opening it for her, right? The third car is also on the first floor, but in order to get to it, you'll have to go even higher - using another plank 79.