"Death Toll: Boathouse": Items
Under any difficulty setting, a health pack and pills will spawn in the bathroom across the field from the house.
"No Mercy The Sewer": Big Explosion
At the beginning of the sewers, if any gas tank catches fire or is shot, the entire station explodes into flames.
"No Mercy: The Apartments": Shortcut
As soon as the level starts, look over the edge of the building and down to the street. Notice the box-like object that is partway down. Drop down to it. Although you will take some damage, you will still be alive. You can then drop down to ground level and continue the level.
Blood Harvest Level 2: Easy Win As Infected
In Versus mode, there is a warehouse-type area immediately after the starting safe room. As a zombie, quickly run back to the emergency door on the other side of the warehouse. There should be a forklift near the door. Spawn and push this forklift in front of the doorway. Note: You may need to break the white door in front of the emergency door to get the forklift all the way in front of the doorway.
Dead Rising Reference
The amount of zombies you have to kill for the "Zombie Genocidist" achievement (53,595), is the same zombie kill count and achievement in Dead Rising.
Death Toll: See Newburg Burning
You can see the city of Newburg from the "Dead Air" episode burning at the end of "Death Toll".
When Hunters are on fire, their pounces and attacks on Survivors do significantly more damage per hit. Use this to your advantage and deliberately set yourself on fire with the many fire pits or burning cars, then attack. This allows you to easily down Survivors. Note: This only works for Hunters, not Smokers, Boomers, or Tanks.
To kill a Tank faster, throw a Molotov cocktail or a gas tank and shoot it. When the Tank is on fire, shoot him with an assault rifle.
To kill a Witch faster, throw a Molotov cocktail. When the Witch is on fire, shoot her with an automatic shotgun.
Easy Kills As Infected In No Mercy, Level 3
The Survivors must jump into a sewer hole at a certain point. As an Infected, use this to your advantage. While playing as a Smoker or Hunter, hide behind one of the large canisters in the room. Once one of the Survivors open the hole and are done checking the vicinity, they will jump in. Due to the fact they must jump in one at a time or get stuck, make sure you have a clear view of the last one in line. Once all three are down and the fourth Survivor is still up, pounce or grab him or her. By doing this, he or she will not be able to be saved, unless someone throws a Molotov cocktail or pipe bomb.
Easy Way Of Defeating Tanks
The recommended weapon for killing tanks is the automatic shotgun. Because it is fast and also packs a punch with its great amount of damage.
Easy Wins As Infected In No Mercy, Level 3
This trick works best as a Hunter. Before you spawn in the No Mercy campaign, Level 3, go all the way to the very end, at the hospital. Once up the ladder, turn to your right, and there should be a dumpster. Move it all the way over to the manhole, and one of two things will happen. It will either fall all the way down, which is bad because the Survivors can't move it; or it will partially fall in. The survivors cannot move this at all. If you are a Tank, you can move a car over it, which is better than the dumpster. From here, do not puke on them as a Boomer, as it will attract the Horde. The Horde will try to move the object away from the manhole. Then, attack them as Hunters and Smokers. They may shoot you, but every so often, you can hurt them until finally they die.
Easy Wins As Infected In No Mercy, Level 4
Before you spawn, go all the way up to floor 28, where the elevator lets out. Just outside of the elevator is a generator. Move it in front of the elevator door. If the Survivors know what you are doing, they can move it. It requires three survivors to move an object. However, if you have someone else on the Infected side, they can go a little bit further and move the forklift in front of the doorway.
When using melee (LT), press Y, LT repeatedly. You will switch weapons and melee. This helps to complete the game on the Expert difficulty from hordes of attacking zombies.
Tanks will float when dead.
Free Roam Camera
Note: This has only been tested on No Mercy. Enable the "Play against NPCs only on Versus Live" glitch. Kill all of the survivors. Then, go back to the respawn point. Have all of the infected up on the rooftop. Jump down on the Hummer. It will kill all of the infected. Wait for a few seconds, and you will now have a free roam camera, like on the PC version of the game. There are no secrets, but there is a mini-city of No Mercy underground that is very interesting.
Use the following trick to get a free roam camera without all NPC characters. Note: This only lasts for a very short time. It also works best if you are at a place where people can jump off somewhere to die. Have a rigged team, where four of your friends are on the NPC team and three of your friends are on Infected. Then have all eight people jump off. They will all die, and you (The Infected) should have a free roam camera. Note: This was tested on No Mercy: The Hospital.
Get Of The Roof
Okay in the first level if you don't won't to go through all of the house you can skip it.
After you pick your weapons you can see a place in the roof were you can jump through the glass. Go to the edge and jump on it, across on anoter building (look down a bit) you should see air conditioning boxes. Jump down on them and then then jump on the dumpster and you are there.
Get Revived By Infected
A Tank and Hunter can revive you if you become incapacitated. Hold X when you are near an incapacitated person if you are infected.
In some of the newspapers seen throughout the game, Dr. Breen from Half Life can be seen.
Invincibility While Reloading
Press B to reload, then hold LT to knock back attacking zombies while reloading your gun.
Keep CPU Characters From Healing You
When offline, there is a way to keep CPU characters from healing you. When a CPU character is trying to heal you with first aid, take out either your own first aid or pain pills. The CPU character will immediately stop healing you. Note: As soon as you put your healing item away, they will try again. This is useful when trying to get the "Unbreakable" achievement.
Kill Two Zombies With One Bullet
Use a sniper rifle and zoom in on a group of zombies. When you see a zombie standing behind another one, shoot at the one in the front. The zombie in back will also get shot.
Left 4 Dead Self-references
In the hospital levels of "No Mercy", you can find a lot of X-rays with only four fingers. This is a reference to the game's cover art.
If you are an Infected when the elevator in "No Mercy" is activated and moving down, the number of what floor it is on will not change from "04", which is a reference to the "4" in the game's title.
In the hospital starting safe room of "No Mercy", there is graffiti on the wall reading "I killed..." and then lists different variables, including 53,594. This is the number of Infected you must kill to receive the "Zombie Genocide" achievement.
Go to any mounted minigun on any level. Stay behind it and start to melee it. You can do this by yourself or get other people to do this. Every time your gun hits the minigun, its launching strength will increase. Once you hit it enough, jump on top of it. This will either make you bounce very high or launch you across the map to your death. Bouncing straight up on it allows you to get to unreachable places such as buildings, airplanes, barriers. etc.
No Mercy Gas Station Lure Tank
When on No Mercy's Gas Station level have a player pull the switch to lure in the horde. Eventually a tank will appear in the fighting. If the survivors are desperate they can send out a survivor to distract the tank. The survivor will then run to the Gas Station with the tank following him (hopefully). After that have him or another survivor blow up the Gas Station. The tank will be dead but so will the player that lured him there. This is a good way to have low-health survivors heal in this area.
No Mercy Level 3: Easy Way Through
Over by the trucks is a door that you can open later. However if you have some people meleeing it, it will eventually break.
No Mercy Level 3: Easy Win As Infected
This trick works best as a Hunter. Before you spawn in No Mercy level 3, go all the way to the very end, at the hospital. Once up the ladder, turn to your right and there should be a dumpster. Move it all the way over to the manhole and one of two things will happen. It will either fall all the way down, which is bad because the Survivors can move it; or it will partially fall in. The survivors cannot move this at all. If you are a Tank, you can move a car over it, which is better than any dumpster. From here, do not puke on them as a Boomer. It will attract the Horde. The Horde will try to move the object away from the manhole. Then, as Hunters and Smokers, you can just attack them. They may shoot you, but every so often, you can hurt them until finally they die.
In the warehouse near the end of the level, immediately after the area with the gas station and the lift, there is a forklift which you can use to block the door the survivors must go through. When the level starts, do not spawn. Instead, quickly go to the warehouse. When you get there, spawn and start pushing the forklift to the door. To push the forklift, keep attacking it. It will move very slowly but you will have time to push it before the Survivors reach it. The only way the Survivors can move it is by throwing pipe bombs at it repeatedly.
No Mercy Level 4: Easy Win As Infected
Before you spawn, go all the way up to floor 28, where the elevator lets out. Just outside of the elevator is a generator. Move it in front of the elevator door. , if the Survivors know what you are doing, they can move it. It will require three survivors to move an object. However if you have someone else on the Infected side, they can go a little bit further and move the forklift that is there in front of the doorway.
No Mercy Subway Door Glitch
In No Mercy subway get to the part where you open the garage door that turns on the power. Beside the door there should be two tanks with a little circle sticking out of them. Try to jump on the circle, then try to jump on top of the tank. When you're on the tank jump onto the door.
No Mercy: Easy Kills
In one part of the No Mercy chapter, the Survivors must jump into a sewer hole to enter them. As an Infected, use this to your advantage. One must be a Smoker or a Hunter. Do not spawn; instead hide behind one of the large canisters in the room. Once the players open the hole and are done checking the vicinity, they will jump in. Due to the fact they must jump in one at a time or get stuck, make sure you have a clear view of the last one in line. Once all three are down and the fourth Survivor is still up, pounce or grab him. By doing this he will not be able to be saved, unless someone throws a Molotov or a pipe bomb.
One Shot Kill With A Pistol
When using your pistol, if you shoot and hit the melee button just a split second afterwards (it should look as though you meleed, and shot in the middle) you should get an instant kill with your pistol. Note: This was only tested on easy mode.
Open The Door After Completing A Level
At the end of the level where the safe room is located, when closing the door keep tapping X. When the door closes, it will open and the level will be finished. The door will be closed the next day.
Orange Box Reference
Near one of the escalators in the subway, there is an ad for "Orange Box" Juice, which is a reference to Valve's Orange Box game compilation.
Play Against NPCs Only On Versus Live
This trick can be done with two to four players. When in the lobby, have someone change to any character except for random or infected. Then, have the other person (people) change to infected. Have the person on survivors go to "Change Character" and highlight the "Infected" option. Start the game and have the person switch to infected before the game finds a dedicated server. The game will start, and there will be no one on the other team. It will take about two to five minutes before the NPCs open the door and leave the safe room. Note: If you kill the survivors or the survivors win, the game will not end. If someone joins the other team, it will be fixed and the game will continue. This glitch only works on the first levels of Blood Harvest and No Mercy.
This works best with shotgun but works most weapons, while you are reloading your weapon that takes a while, if you are attacked by a zombie you can smack them using the smack button without stopping the reload process and is essential if you are trying not to take damage if you are low on life. (you may already know this but if you don't then you do now)
Star Wars Reference
The APC in "Blood Harvest" is marked "TK-421" is a reference to the stormtrooper in Star Wars that Luke Skywalker and Han solo incapacitated.
Stay Alive Longer
When hordes of Infected appear, find a room with a door and no windows. Go inside and close the door. The Infected may break the door, but when you see a hole in it, shoot the Infected trying to break it down. Your teammates can handle most of the Infected.
Team Fortress 2 References
Before the finale in "Dead Air", while still in the safe room you can sometimes see a box which advertising Team Fortress 2.
John Slater, who is the voice actor for the person who drives the boat in "Death Toll", also voices the sniper in Team Fortress 2.
If you are low on health and need somewhere to hide, find a bathroom stall. Go inside the stall and close the door. The door never breaks down. This works well if you are trying to heal yourself.
Zoey Has Three Hands
On the movie poster for "No Mercy", look closely to see that Zoey has three hands holding her gun.