Half-Life 2: Episode 1 - Chapter 3: Lowlife - Zombies in the Dark

Okay. Your escape has gotten a lot more complicated. Alyx is freaking out though. Wait a moment for Alyx to recover and kill the forcefield. Then advance along the train tracks. The room ahead is full of zombies, so hang back and let Alyx kill them. It doesn't seem like the turret is functioning, so you just have to focus on the zombies. You can use the gravity gun to throw some boxes around if you really want to help. Advance and stay close to Alyx. You’ll need her firepower. Use the gravity gun and some boxes to help out. Get to the end of the room and enter the dark hallway. The door at the end is sealed though. Look to the side to find the air duct behind a barrel. Knock the vent off and go inside for a little more vent crawling.

Crawl along and grab the health vial with the gravity gun. You don’t need the flare so just leave it or drop it down the vent. Turn to the left and climb up the ladder. Enter the next section and look down through the broken vent. Use the gravity gun to kill the headcrab below. All of the zombies are dead, so don’t worry about them. Drop down and use the flashlight. Look for the cage in the corner. Use the gravity gun to grab the red flare. This will activate it and give you a nice light source for the next minute. Go ahead and turn off your flashlight to recharge the energy.

Use the gravity gun to pull the shotgun and pistol up and over the bent part of the fence. Break the supply box and get the extra ammo that should be inside. Go ahead and get more health and suit energy from the open lockers in the corner. When you’re ready to go, pull out the pistol and shoot the lock on the fence door. Go through and use the flashlight to find the fuse box on the wall. Open it and then use it again to restart the power and open the door for Alyx. Use the gravity gun to knock away the cars blocking your next door.

Now, there are 2 things you’ll be short on for awhile. Light and ammo. If you try to kill all the zombies yourself, you'll always be out of ammo. Alyx can accurately fire at anything though, as long as she has enough light. You need to use the gravity gun and the flashlight to get through these tunnels.

Go through and use the gravity gun to hit one of the zombies with the gas can. This will set it on fire and light up a good portion of the tunnel. Move to the left. There’s a dead civilian back here with a shotgun. Grab the extra 6 shells and start pushing forward. Help Alyx kill the 3 other zombies wandering around by the truck. Once they’re dead or you feel safe, turn off the flashlight and let it recharge. When it’s ready, push forward to the dead antlions. Use the gas can on the zombie and use the gravity gun on any surviving antlions. Alyx can easily kill them while they’re on their back. With the coast clear, push forward and grab some more ammo from the dead body. Then get onto the train.