The Subway

The Subway is the second chapter of the first campaign, No Mercy. It begins in a safe house at the beginning of the decimated subway of Fairfield. The door behind the Survivors has been blocked with various heavy objects, as to further keep the Infected out. In front of them at this point are four first aid kits, an ammo cache, and Tier 1 weapons.

This was one of the two chapters of No Mercy featured in Left 4 Dead ' s demo, though only the first half of this map is available in regular play, with a safe room just after the Crescendo Event. In the full game, however, it goes beyond the building and into a street, eventually into a pawn shop where the next safe house is.

Campaign
When starting from this chapter, the AI Survivors will grab:
 * Bill will grab a submachine gun.
 * Francis will grab a submachine gun.
 * Louis will grab a submachine gun.
 * Zoey will grab a submachine gun.

When the Tier 2 weapons are found, they will grab:
 * Bill will grab an assault rifle.
 * Francis will grab an auto shotgun.
 * Louis will grab an assault rifle.
 * Zoey will grab a hunting rifle

Otherwise, they will keep the weapons they had when you started the campaign. (See The Apartments for a list of weapons they will grab there.)

If you're starting on this chapter, make sure everybody grabs a first aid kit and a weapon. They are entirely necessary to everyone's survival. If you started in the first chapter, heal up if you need to and take what you can. Despite the AI's propensity to grab the submachine gun here, it's actually recommended you take (or keep) the pump shotgun. Luckily, you can find Tier 2 weapons later on in this level, so look out for those.

If you're trying to be careful (which is definitely recommended in this game), you can shoot through the bars of the safe room door. Kill any zombies you see, and once everyone's ready, open the door.

What to do from here is up to you. However, it's best to clear out any other zombies that were out of sight when the door was closed, and then jump to the small remnant of the floor on the other side. Look under the ground you were just standing on, and you'll generally see quite a few zombies. Shoot what you can from there and jump down. To be safe, go under there and kill anything else. Be careful, though! There's a massive hole in the ceiling, and Infected like to hide up there. Don't get caught off-guard by a Boomer.

Now, there are two ways to go:


 * 1) A set of stairs, which are on the left. This is a slightly safer way to go, because everything is in broad sight and it quickly gets you to the next area.
 * 2) To the right is a dark hallway, near the end of which is a small duct. If you go down there, break the vent open and exit quickly.  You will be above the staircase from the other route.  It is not recommended to go this way as you will fight more zombies than if you took the stairs.

In either case, if you look to your right, you'll see a small set of stairs. Occasionally, there may be something useful up there, such as pipebombs. If you want to be thorough, check there.

Regardless of where you go, both lead into a small area with escalators and ticket booths. There's a table in front of the booth to the left, and if you're lucky, Tier 2 weapons will spawn there. There will sometimes be an ammo cache on the table, if the weapons haven't spawned. What you grab is up to your style of playing; all of the weapons have their pros and cons. Also, be sure to check the booths themselves. Much of the time, there's a second pistol, pipe bombs, or pain pills. Needless to say, it's at least worth giving a look. If you continue to the left, there's further sets of stairs, which you need to ascend to keep going. Again, both lead to the same area, so it doesn't really matter which you take. Just take a look around once you get up; you never know what you'll find.

It's fairly easy to figure your way out along the wrecked tunnels. Keep an eye out for weapons, though, if they didn't spawn before! There might be some on a table with an ammo cache on it near the last train, or on yet another table on the other side of a train you need to go through. You'll eventually enter an underground area. If the weapons still haven't spawned, they should be in a table at the end of it.

As you go up the stairs at the end of that place, you'll enter a room with three big (what look to be) generators. On the far wall, there's a door, and a slightly ominous switch next to it. That's right; that triggers the first Crescendo Event in this campaign. Hitting that switch will summon a moderately large horde. Luckily, there are some supplies to the right inside of a relatively small room... and a big hole in the corner. There's a first aid station in there and a Minigun. However, if you choose to man the turret, make sure you have someone covering you! All kinds of the Infected can and probably will come out of that hole; Smokers might even drag you back down there! However, you can still get back up to where you were, but it's dangerous getting up there alone. Take a good look around before you hit that switch, too. There's some gas cans lying around, and sometimes Molotov cocktails as well at the door you just came through, which you can use to help you in keeping the upcoming horde at bay, such as setting them off at key points of entry for the Infected. Basically, flaming zombies are dead zombies, one way or another. When everybody is set, hit that switch, and get ready for a fight.

Tactics for Crescendo Event: There are basically two ways to deal with this, Fight or Flight.

Fight:
 * Everyone can get into a corner and melee, if it's an all-human team. Any break in the formation—especially to go save an AI who won't join you!—can mess everyone up.
 * Everybody gather around the Minigun, and send somebody out to the switch. When it's activated, have them run back, and light the hole on fire. Focus your fire on the other entrance into the room while the zombies burn down below. After the flames have died down, have two people watch the hole while the other two watch their backs until it's clear.
 * Try to stay under the catwalks. The Infected will have to fall down in front of you or run in front of you: they can't come at you from behind, no matter how hard they try.
 * Use several pipe bombs. This is one of the easier tactics to use.

Flight:
 * This one is very simple. Once the door is open enough for you to get through, run. There's a room above with an ammo cache and Tier 2 weapons.  If all four Survivors can make it here, you will have an easier time of fighting off the rest of the horde.  However, a special infected will sometimes spawn outside the exit of the room (even a Tank), making your fight that much harder.


 * Another tactic would be to have everyone wait on the stairs that come into the room. Use a gas can at the bottom of the stairs leading into the large room with the pillars, and a molotov near the entrance to the other room at the top of the stairs. Remember, this will work against you if a Tank happens to spawn.

It's up to you whether or not you wait through the horde, or try to get through the door as soon as you can. It's actually somewhat advised that you try to hold your position, as trying to escape from the horde can be fairly difficult, and you never know what you'll run into ahead. A Tank plus a horde can be a shockingly terrible formula for disaster.

Once the horde has been taken care of, get what you can from the room and get into the hallway. From here, there's another two ways to go, and both, once again, go the same way:


 * 1) Go the regular way; continue to advance down the hall, which will let out into a desk area, off to the right of which may be even more weapons.
 * 2) Go straight into the office area with two windows, from where you would be able to see the helicopter if you hurry. There's a ledge immediately outside of those windows, and from there you can jump down without taking any fall damage.

Once you get into the street, keep going until you see the pawn shop... and a car with blinking lights. Just as in the last chapter, shooting it or touching it in general will set it off, starting a Panic Event. Unless you're looking for trouble, try your best to avoid it. If you accidentally set it off, hurry into the safe room that's just inside of the shop. Once you've closed that door, they can't get you—just make sure everyone got inside. Now, get ready for The Sewer.

The Survivors
Now that humans are now controlling the Special Infected, things can only get harder. However, they can't spawn until you open that safe room door. That doesn't mean that you should let them have a good chance to find just the right spot, though! Hurry up and get your supplies, and get running. Most of the time, they will spawn in the ceiling above you, and can get you from the hole. Make that an irrelevant plan: once you open that door, everybody needs to drop down the hole together, and just keep running with each other. Never separate. Do not go to the right, because the vent is another popular spawn point for the Infected; it's small, with only one or two exit points, thus making it an excellent ambush point. Go down the stairs, look for weapons and other supplies, but don't stop for long. The longer you stay still, the greater chance they have to one-up you.

When you reach the point of the Crescendo Event, don't dilly-dally. Hit that switch as soon as you can, clear out the horde from that power room, and keep moving! Be careful if you hang around the minigun, though. A favorite trick of the Smoker is to drag you down that hole, as aforementioned, but the humans will be even more vicious about it. You will definitely need cover if you decide to man the turret. In any case, though, get through that door and up the stairs as soon as you can. Get some ammo and get outside as fast as you can, but stick together. Never give them a chance to catch anyone alone.

Once you're in the street, you're almost there! Be extra careful about the car, as the Infected will more than likely hide around it. Just hurry into the safe house, get everyone that you can inside.

The Infected
Boomers: Fragile as you are, you can still be the biggest pain in the world if you really work hard. Hide around corners and generally around obstacles the Survivors will probably pass. If you can't find a corner, just rush them, go kamikaze; even if you miss, maybe they won't. That hole in the ceiling at the start is an excellent place to spawn, as well. Drop down on the unsuspecting Survivors. If you can, try to get on rooftops, as well. If there's a Witch, hide exceedingly close to her; if they shoot you, it disturbs her. If they don't, you have a chance to vomit on them... though they'll generally shoot you. Or, if a Tank has spawn, try your best to get at least someone. The Tank can keep the rest from aiding your victim, or it can focus on your victim, further exacerbating their plight and making their doom more and more imminent.

Hunters: Certainly, you are a force to be reckoned with, though it's a general rule of thumb to see your prey before they see you. Hunters work best in ambush situations. Another rule is to not attack a group unless you're trying to distract them, or simply scare them. Try to hide in small spaces, though. Pounce people who wander off. Always remember that you have a strong melee attack, so if you can't quite pounce, feel entirely free to melee. Hiding around Witches and cars with active alarms is also quite devilish, and effective. Additionally, if there is a source of fire around, jump through it. Your common sense might tell you to avoid it, but Hunters deal significantly more damage when they are on fire as opposed to when they're not. Though you will die eventually, you may be able to take someone out with you.
 * Note: After a recent update, Hunters caught on fire by environmental flames (i.e. fires in barrels or pre-existing fires) will not deal extra damage. Instead, only a Hunter caught on fire by a gas can or molotov will deal extra damage, and even then not as much as before.

Smoker: Smokers are most definitely not meant for close quarters. Stay out of them. Try to pull people back, and generally slow them down and act as a giant nuisance. Try to separate them, as well! Collaborate with your teammates to keep them from getting to the next safe house. The gaping hole in the ceiling is a great place to start. Also, at the end of the level, there's a street with a car near the end of the road. This car has an alarm that's just dying to go off. Help it along; stand around this car and attempt to pull Survivors dangerously close to it. One way or another, someone is bound to set it off, and set them up for a grand fall. Also, there's an instant kill location for the Smoker if they stand on the rooftop above the barbed wire fence that's down the alley, off the road leading to the pawn shop. If a Smoker drags a Survivor from this position, it will pull them up into the barbed wire on top of the fence. At this point, the Smoker's tongue will break, and as soon as their victim hits the ground, they're dead.

Tank: Fortunately, the Tanks have a relatively high chance of spawning here, allowing you to wreck the Survivors even more than previous Boss Infected, potentially even more than any Witches that spawn. It's great to get them into closed spaces, or if you're on that final stretch of road, try to throw cars at them. If they hit, it's an instant incapacitation. At this point, you can either throw it at them again (which would kill them), or focus those who are still moving, leaving the downed for the proverbial birds; your teammates. However, if you can, try to avoid the car with the alarm. If you hit it, the alarm will break, and anybody who manages to survive your onslaught will be able to get to the next safe point without that risk of summoning yet another Horde.

Survival Mode
The Survival Mode name for this level is The Generator Room. The areas that are open are the basement part with the columns, the generator area, and the upstairs. It is activated by opening the door.

Trivia

 * The area after the safe room's location in the demo is still accessible in the demo via the "noclip" console command, but the AI Director will not generate enemies in the area, nor is there any safe room for the Survivors to reach.
 * There is a Safety Checklist in the safe room at the end of the chapter. It has a list of things for Survivors to do to ensure they don't become Infected, as well. It is a poster that is produced by CEDA, which is believed to be a company connected to the Infection. The steps read as follows:
 * Seek shelter in fortified, windowless room, preferably underground.
 * Ensure all openings have been securely obstructed.
 * Secure the room with plastic sheeting and duct tape.
 * Listen to your radio for further instructions from authorities.
 * The third item on the list has been crossed out here, with the words "Not Airborne" written next to it. This may suggest that the Infection was once thought to be spread through the air, but was later disproved.
 * Near one of the escalators, there is an ad for the "Orange Box" juice. This is an obvious reference to another of Valve's vastly popular game packages, The Orange Box.