Chapter 1: The Greenhouse
Grab your health and weapons and move over to the top of the wall. You should be able to see the length of the greenhouse, and there will inevitably be infected. Kill them before moving on. Head out of the greenhouse and across the planks – be very careful. It is easy to get pull off by a smoker here, and the consequences can be nasty.
Move quickly into the house at the end of the rooftops. Head through the house, checking for weapons and health, and back out onto the rooftops. Watch for hunters and smokers here, you are extremely exposed. Head up the ladder and down into the next building, where you should, again, look around for goodies. Head down the stairs and into the room with the windows.
See the Harbor View Hotel across the way? That’s your safe room. This level is shorter than you think. Move as fast as you can across the street (throw a pipe bomb if you found one) and you’re home free – the special infected will likely make a move here, so be on your guard.
Chapter 2: The Crane
Move out of the safe room and clear the immediate area of infected, including the dimly lit area outside. This is a great place for hunters to rack up enormous pounce bonuses, so you want to be through here as fast as possible. Go quickly out, over the fence, onto the boxes and up the ladder to the left. Keep going up the fire escape until you reach the window that leads into the room. Enter to the left, through the bathroom. Check for weapons and health in the room and the one across the hall, then start moving. Check each of the rooms in turn, but quickly, just long enough to check for the glowing outlines of weapons or health.
Head up the stairs, around the corner, and into the room across the hall – this is a great place to find explosives, so look around. Shoot out the right window and move onto the roof. You should be able to see the crane. Have everyone stack up by the switch before activating it – it’s the safest place. Watch out for smokers and you should be fine. As soon as the dumpster lands, climb over it and onto the rooftops. Hurry across these, and keep looking out for smokers, as they can pull you over the edge – not a fun place to be. Move into the office building (through either entrance) and move quickly into the room with the booze along the back wall (check here for molotovs). Run across the planks and left, into the room with the health.
Go down the stairwell, and you’ll find yourself in a room with cubicles. This is a great time to use the hunting rifle’s scope – zoom in and pop the heads of the infected you can see before moving on. There are lots of room here, but generally they have more infected than goodies, so I would skip them if I were you. At the bottom of the stairs you will find a reception desk, which usually has something good, and several rooms which you should check. You can go out the back here to get to the safe room, but unless you’re really worried, its probably better just to make a break for it. Once you reach the storage place, you’re safe.
Chapter 3: The Construction Site
Move out of the safe room and head left, following the path quickly. Once you reach the construction site, you want to clear it of infected and move into the large unfinished building. Climb up the ladder onto the scaffolding and have someone shoot the barricade to start the horde event. Stay out of easy pouncing or pulling locations and you should be fine, but stack up in a corner if you’re worried. Once the barricade is down, move down the alley, but stop in the first room on your right to look for weapons and health. There may be ammo or weapons at the end of the alley as well.
Once you exit, you will be facing a large power station. You can go around the power station, but it is safest to move through it, so stay close and move quickly. Once through the second set of pylons, turn right, and go into the room with the forklift. Check in the back for goodies. The next room will have a health kit and two easily defendable doors – this is a good place to stop and heal up, if you need to. Keep moving through the building – check the bathrooms in the next area for explosives – and soon you should be able to see the airport. Use your assault rifles and hunting rifles to clear the area, then move across.
The parking garage is on the same side that you exit on, but you need to walk around the debris to get to it. It’s full of dark corners, so keep your eyes peeled and stay together. Some cars can also alert the horde, so watch your fire. Once you’ve gone up the ramp, it’s just a quick trip up the stairs and across the skybridge, and you’re safe.
Chaper 4: The Terminal
The open wall in the safe room gives you a great vantage point from which to shoot infected, so do so before leaving the safety of the room. There are a couple of places just outside the safe room that special infected can jump you from, so move quickly across the room into the conference center. This series of rooms is full of goodies, so take the time to check, but don’t dawdle. Exit left back into the terminal, and you’ll find another good place to stop and clear the room of infected. Exit down the escalator and take the time to check all around for weapons and health.
When you’re ready, start the van and stack up near the desk at the far end of the terminal – it will likely have explosives too, so grab what you need. The nice thing about this horde event is that it happens quickly – in moments you can follow the van through the hole it made and set up in one of the nice, enclosed rooms, if something is going badly. Once you’re safe, head toward the baggage claim and into the conveyor area. This area isn’t particularly dangerous, but it is awkward enough to give special infected an advantage, so move through it as fast as you can – stick to the catwalks if possible.
Exit onto the main terminal again. Do not, under any circumstances, walk through the metal detectors. They still work, and will alert the horde. Also watch out for smokers trying to pull you through. There should be ammo or weapons underneath the Atlas statue. Check the Duty Free for goodies, then head up the escalator. You’re fairly safe from here to the safe room, but it’s a surprisingly long walk, so hurry up. Head into the safe room, and you’re almost done.
Chapter 5: Runway Finale
Exit the safe room, wait for the plane to crash (bummer!) then head out onto the runway. This is pretty simple, just head toward the only plane still in one piece as fast as you can. Once you reach the minigun and weapons, stock up, and get ready for a fight. This is one of the more unpleasant finales, as there’s not really a good place to stand and fight. On the far side of the plane is a good spot, as you can see the infected coming. The minigun is always good, if your team is competent, and you can also wedge yourself in the corner behind it, but watch for crafty smokers. Getting on top of the air conditioners gives you plenty of fire lines, including covering someone on the minigun, and makes it easy to knock back the horde, but you are vulnarble to smokers on the roofs of other buildings. The other thing you need to watch out for are the baggage carts lying around – even idiot tanks will know enough to chuck them at you, and that’s an instant incap. Stay clear of them at all costs. After the second tank, get to the plane, but be aware that the door opens agonizingly slowly, so don’t neglect to kill infected.