The Tunnel

The Tunnel is the second chapter of the fifth campaign, Blood Harvest.

The Survivors must fight their way through a railroad repair workshop to reach the tracks which run through a semi-destroyed underground tunnel. On the way, they are forced to open an security-alarmed emergency door which triggers a Crescendo Event.

The chapter ends at a safe room inside the tunnel.

This chapter features high threat levels from aggressive loitering Common Infected as well as a full complement of Special Infected, up to and including a Tank.

Campaign
When starting from this chapter, the AI Survivors will grab:
 * Bill will grab a submachine gun.
 * Francis will grab a pump shotgun.
 * Louis will grab a pump shotgun.
 * 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 in the last chapter. (See The Woods for a list of weapons they will grab there.)

Players start on third floor of a train car repair workshop. Similar to the early levels of other campaigns, there are only Tier 1 weapons in the safe room.

On exiting to the hallway, players should search the surrounding rooms. The two rooms on the left often contain Pain pills, Molotovs, Pipe bombs, or an extra pistol.

Descending the stairs brings players to a suite of interconnected offices overlooking the workshop. There are two possible spawn points for Tier 2 weapons on tables here, one in the center room, one in the room directly to the right of this one. Note that the offices can also be home to Pain pills, Pipe bombs, Molotovs, and an extra Pistol. Loitering Common Infected can be sniped from the office windows and external catwalk.

These offices are normally the venue for an attack by a 'hurry-up' horde who will approach from all available directions. Their assault is usually reinforced by a Smoker and Boomer.

Players proceed along the catwalk, opportunistically sniping the Common Inflected loitering in the area below as and when they come into view. A collapsed yellow-painted steel beam at the far end of the gantry allows easy access to the ground level. Alternatively, players can jump down using ventilation trunking and railroad cars as convenient.

This is a known Tank spawning location. However he fights at a disadvantage because players can easily move around and evade his attack. For example, a sound plan is simply to run back up the yellow beam onto the catwalk, spread out and cone him with gunfire as he tries to climb up in pursuit.

Once the ground level is secure players are free to explore. It is a good idea to head on back to some storerooms located under the offices that were exited earlier. These rooms usually contain a supply of gas cans and propane tanks. A plan (see 3. below) is to scavenge these and carry them over to the doorway leading out of this area. Lay these explosives out in front of the door next to the office table bearing supplies such as ammo and weapons. Take all the time needed, there will be no attack. A word of caution though: returning upstairs to the offices for a fresh weapon may trigger an aggressive hurry-up horde.

In the room ahead of the yellow beam is an alarmed emergency exit door bearing the notice ''"Emergency Exit Only, Alarm Will Sound". ''Players should not touch the alarmed door as yet.

The medical cabinet in this room will contain pain pills and rarely, a First aid kit. Note: There is never a first aid kit on Expert here.

The emergency exit triggers a Crescendo Event. There are various ways to approach this:


 * 1) Fight from the room where the door is activated. If the crates at the back of the room are broken up, all four Survivors can put their backs to the wall and fight from there. When simply fighting from the center of the room, Infected can attack from three different directions―the two opposite doors and from the vent above. Fighting backs to the wall effectively covers all three of these and cancels out the enemy's advantage.  (However if playing the L4D 2 port a Spitter can break up your formation.)
 * 2) Fight from the corner beside the table with ammunition or tier 2 weapons. The advantage to this is that the team cannot be attacked from behind and they effectively have infinite ammunition.
 * 3) Open the door to set off the alarm and sprint back up the yellow beam to the catwalk. As the first of the horde emerge from the doorway down below, set off the ambush of gas cans and propane tanks set out around the doorway. Once the horde has been defeated, it is a simple matter to descend the yellow beam, stock up on ammo from the desk and move on. Note: this method is well worth trying as it is arguably the most efficient and safest way of defeating this Crescendo / Panic event.
 * 4) Open the door, close the door, and backtrack to the large train shed for combat on open space. Whilst effective, this method is also dangerous if someone gets stuck on a Special Infected or if the team is uncoordinated. It is therefore not recommended on higher difficulties.
 * 5) The final, and least recommended, method is to "outrun" the Infected. Prepare the team and charge out once the door is open. By moving far enough down the level, the crescendo event's Infected will stop spawning. This method can lead to horrible situations where the Survivors encounter a Tank in front of them, and turn to leave, only to find the horde behind them. Due to its extremely high risk, this method is an option only if a team is not playing to win on an easier difficulty.

The emergency exit door leads to a large narrow industrial space containing roof-high cisterns and pressure vessels. Teams have two options: take a staircase to an upper level catwalk or turn left and proceed at ground level.


 * Choosing the catwalk makes it possible to check various rooms along the way for supplies until an exit can be made onto an overhanging roof above the tracks and tunnel entrance.


 * Staying at ground level brings teams to a door leading directly onto the tracks  Otherwise heading to the left will lead to a door on the right which also leads out onto the tracks and tunnel.

Regardless of the route taken, teams will encounter the usual loitering Common Infected as well as a couple of Specials - including a Witch and possibly a Tank if he has yet to spawn.

The area at the tunnel entrance to the tunnels is thickly populated with aggressive Infected and at least one hurry-up horde is sure to spawn. A table at the start of the tunnel will bear weapons, pills or throwables. Before proceeding it is sensible to check the immediate surroundings thoroughly for additional supplies such as a gas can or propane tank.

There are two minor routes through the tunnel which quickly meet up and lead to the same destination. The route to the left is more direct whilst that on the right follows a side tunnel up onto the roof of a train car. Once the paths meet, the route ahead takes teams over an obstacle course of crashed train cars filled with dark and complex spaces - and Infected. The ultimate goal is a small side passage on the left which ends in a safe room.

The tunnel is thickly populated with loitering Common Infected and the entire map is ripe with Special Infected. Smokers are a serious danger as they can spawn at the rear and snag a lagging player who can be badly harmed before team mates can scramble back over the obstacles to help. Hurry-up hordes too can make life difficult as they also swarm in from multiple directions simultaneously. A team which is hurting and low on ammo can thus be in bad shape by the time it finally reaches the safe room.

However the most serious risks in the tunnel are two-fold. Firstly, a Witch can spawn towards the end of the tunnel and even right outside the safe room door. Secondly, if he had not yet put in an appearance, a Tank is highly likely to spawn in the final stretch as teams reach the top of the rail tank car. Worst case,  he can even appear directly in front of the safe room.

In sum, combat in the tunnel is guaranteed to be intense and close to unremitting from start to finish.

Once in the safe room, teams prepare for more of the same when they face what is coming up next: The Bridge!

Left 4 Dead 2 Version
The map is unchanged apart from weapon and enemy profiles.

The Survivors
Now that humans are controlling the Special Infected, things can only get harder. However, they can't spawn until you leave the safe room. 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!

Throughout the level, keep in mind that you are playing against human players. They will not wait for you to come to them, and if they do, it's because they have an ambush location that could be deadly to you and your team. With this in mind, you need to keep moving. However, moving blindly could be your downfall―move quickly, but with caution.

This level is not too bad for the Survivors. There have certainly been worse levels, but overall, you have a fighting chance against the Infected. Remember that your enemies will try to anticipate your moves and will attack when you are vulnerable or alone. Keep in mind the locations that you'd hate to be attacked in and exploit your knowledge as an Infected.

The Crescendo Event will be problematic for an inexperienced team of Survivors. If you utilize the methods for campaign mode, you should be alright. However, remember that your enemies will most likely be aware of these tactics and will exploit their weaknesses. Stick together and cover each others backs. Make sure that everyone is still standing and not being attacked by Special Infected.

This level is a Tank nightmare, it is nearly entirely indoors or in close quarters. The Tank can rip apart any Survivor team, especially a human-controlled Tank. Bear in mind the locations he will spawn and how best to deal with him. Also remember that he can spawn right in front of the safe room. This is one of the worst places for him to spawn as not only is it in close quarters, but it normally takes a tired team of Survivors by surprise. Be sure to pause before heading into the safe room, as the Tank's hulk might glitch through the wall, allowing you to prepare for him.

Also concerning the safe room, when you know you're near the safe room, make sure you are with your teammates before you make a dash for it. If you make a break for it alone, it is not unlikely that a Hunter will be waiting for your arrival and possibly kill you before the others can reach you. Or worse, the aforementioned Tank will spawn. No one can survive the infection alone. Teamwork is essential.

The Infected
Boomers: This level was made for you. You are the sneaky one, hiding around corners and in dark rooms. You stalk your victims, wait for them to be distracted, then―attack! Vomit spews in their direction, they scream rants of anger as they back into defensive positions; waiting to embrace the force of your approaching horde. The interiors of this level are perfect for Boomer ambushes. There are many corners that the Survivors must pass on their journey. If a Tank shows up, do your best to cover as many Survivors as you can. A horde and a Tank at one time is often enough to overwhelm the Survivors. Although rooftops aren't your forte, go for it! You can wait on the rooftop for the Survivors to emerge through the windows below you. Then, you can rain down your putrid bile! If you can cover the Survivors while other Infected are in position, Smokers and Hunters can use the opportunity you created to put the hurt on the Survivors. There's a Witch? Conceal her! Odds are that one genius Survivor is going to shoot you and the Witch in one go.

Hunters: Certainly, you are a deadly foe worth marveling, though it's a general rule of thumb to see your prey before they see you and revel in your excellence. 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. Remember all of those times you were pounced by a Hunter and it couldn't have happened at a worse time? Well, exploit that knowledge. Think like a Survivor, and attack when they're vulnerable.

Smokers: Indoors. This is not so great for you. However, the interiors are generally wide open. Open spaces are generally good because you can drag them far away from their friends. Closed spaces are not so good. Experienced Survivor teams will often adopt a "squad formation." This usually consists of three facing the front and one covering the back every so often. Let this be their downfall and snag that rearguard. With no one else watching the back, it may take the Survivors a few vital seconds to realize what has happened. As with the Hunter and the Boomer, don't underestimate your secondary melee attack.

Tanks: Here, the Tank is strong. Where is he not? He can strike with swift precision and force, breaking through walls of Survivors and charging through seas of lead and fire. Perfect. As with most interiors you are a force to be reckoned with. You can be the very difference between victory and defeat. However, these interiors are fairly open. Because of this, your rock-throw attack can be a lifesaver. Or a killer, whichever way you want to put it. There is also a forklift and freight dollies in the main warehouse, though it may be tricky to hit the Survivors if they're on the catwalks. As long as your enemies are not a team of perfect players, you should be able to do a large amount of damage to those immune annoyances.

Survival
Crates Method


 * This method involves fighting from the room where you activate the door. If you break the crates at the back of the room, all four Survivors can put their backs to the wall and fight from there. When simply fighting from the center of the room, Infected can attack you from three different directions―the two opposite doors and from the vent above. However, if you do fight with your backs to the wall, you can group all three entrances in front of you. This effectively means that they only attack you from one direction. When the Tank arrives, the team can exit through the door to the right and fight him out on open ground. Once he's been dealt with, repeat the method until you get yourselves killed.

Boxes Method


 * This method's strategy is to find two of the tall shelves holding crates and boxes and sandwich your team in between them. If you find a decent one, you can have the Infected only attack you from the front, however, the Tank cannot be dealt in this way. As with the previous method, it is best to head out on to open ground and fight him from there. Once he's dead, return to your position and continue the fight.

Hidden Cargo Method


 * Do not alert the horde just yet. There will be a lot of crates on one of those big shelves. If you climb up there, you will notice a little gap in the boxes. You and your teammates will be able to drop down there. You will be unnoticed by every type of Infected, except the occasional Hunter . This method is very tedious but you can stay there as long as you want and not get caught.


 * To get up here, run up the yellow beam. Turn back in the direction of where you enter the room in campaign. You should eventually come to an I beam leading across to the other side. Cross this. Do not turn. Jump onto the railing, then drop onto the stack right below you. You will not die. Run to the back against the wall, and in the corner by the large vent-like machine, there should be a depression. Walk into this. If you do not fall in right away, jump until you do. You can stand in here. Stay in the hole, no matter what. If even one person stands on the crates and is not in the hole, Infected will attack you. Occasionally, if a Hunter or a Smoker spawns on the second level, it will come towards the railing. They may or may not attack you, so it is a good idea to shoot them.

Rooftop Glitch Method
 * This glitch allows up to two players to be standing on the roof of the warehouse, where none of the Infected can reach you. First, incapacitate all non-human Survivors. Keep in mind you will need at least three human players to perform this glitch. At the start of the round you will see a fallen yellow beam that acts as a ramp to a platform. Go up the beam and look to your left. There will be partially destroyed railing. Jump on top of this railing and then jump forward and move backwards to be incapacitated and holding onto the rail. Now, have two human players help you up. The primary rescuer will help you until the "revival bar" is at 90 percent full. When it is at 90 percent, the primary rescuer will let go. The secondary rescuer's job is to hold the help button the whole time, until the primary releases. When the primary releases, the secondary will continue to help the Survivor up. Continue that cycle for about 2-3 times and the hanging Survivor will be on the roof of the warehouse, safe from all danger. The other players will then alert the horde. They will most likely die, but that does not matter as long as the player on the roof remains alive (and does not go idle), the timer will continue for as long as they wish to stay.

Safe Room Glitch Method


 * This uses the same glitch as mentioned before, but you must go into the opposite corner of the room. Communication is essential. When the person being 'revived' sees a red chair, do it once more, but have the reviver completely fill the bar. You now should be in the safe room. Not only will the infected be unable to get you, you may shoot at them. This can be used to get the Zombie Genocidist achievement. Make sure to never open the door. This is extremely helpful, as unlike with the Rooftop, the player may shoot at the zombies, allowing more enjoyment. An ammo pile is here, so it may be used to keep ammo up.

Vent Method


 * In the room where you activate the door, you will notice on the right are three crates, look up at the ceiling and there is a air vent, Now it is possible to get through this part without activating the door although it may take a few attempts to get it right. There are two crates stacked one on the other; you need to melee these underneath the air vent ensuring that they are still stacked, then melee the other crate until it is besides the two stacked crates, jump from the single crate onto the two stacked crates directly below the air vent. Jump into the air vent and proceed through without having to activate the crescendo event.